(CNN) Russia and England could be kicked out of the Euro 2016 championship if their supporters are involved in further acts of violence at the tournament, UEFA has warned.

UEFA's executive committee told the football associations of both countries Sunday that their teams could face further sanctions -- including potential disqualification from the tournament -- if their fans were involved in a repeat of the scenes that marred their fixture in Marseille Saturday.

UEFA, the governing body of football in Europe, has already opened disciplinary proceedings against the Russian Football Union over its supporters' behavior in Marseille.

It faces charges of crowd disturbances, racist behavior and setting off fireworks Saturday in the southern French city's Stade Velodrome.

Lorik Cana of Albania touches the ball with his hand resulting in the second yellow card .Cana was later ejected from the game.

Lorik Cana of Albania touches the ball with his hand resulting in the second yellow card .Cana was later ejected from the game.

Switzerland's players celebrate their 1-0 victory over Albania with their supporters at the Bollaert-Delelis Stadium in Lens, France, on Saturday, June 11.

Switzerland's players celebrate their 1-0 victory over Albania with their supporters at the Bollaert-Delelis Stadium in Lens, France, on Saturday, June 11.

Slovakia's midfielder Ondrej Duda shoots and scores his team's first, and only, goal. Earlier this month, Slovakia defeated world champion Germany 3-1 while it also overcame Spain during the qualifying campaign.

Slovakia's midfielder Ondrej Duda shoots and scores his team's first, and only, goal. Earlier this month, Slovakia defeated world champion Germany 3-1 while it also overcame Spain during the qualifying campaign.

Wales players celebrate their team's second goal scored by Hal Robson-Kanu. It has been 58 years since Wales last played in a major tournament.

Wales players celebrate their team's second goal scored by Hal Robson-Kanu. It has been 58 years since Wales last played in a major tournament.

Wales fans celebrate their team's 2-1 win over Slovakia in the Euro 2016 at the Stade de Bordeaux in Bordeaux, France on Saturday,June 11.

Wales fans celebrate their team's 2-1 win over Slovakia in the Euro 2016 at the Stade de Bordeaux in Bordeaux, France on Saturday,June 11.

England's goalkeeper Joe Hart, center, looks at the ball going into his net as Russia scores at the end of the game. Russia's 92nd minute equalizer denied England victory.

Fans clash in the stands after the match. The build-up to the game in Marseille has been overshadowed by violent clashes between rival fans and police over the past few days.

Fans clash in the stands after the match. The build-up to the game in Marseille has been overshadowed by violent clashes between rival fans and police over the past few days.

Russian supporters light fireworks after a Euro 2016 match between England and Russia ended in a 1-1 tie, at Stade Velodrome on Saturday, June 11, in Marseille, France.

Russian supporters light fireworks after a Euro 2016 match between England and Russia ended in a 1-1 tie, at Stade Velodrome on Saturday, June 11, in Marseille, France.

"UEFA expresses its utter disgust for the violent clashes that occurred in the city center of Marseille, and its serious concern for the incidents at the end of the match inside Stade Velodrome," UEFA said in a statement.

"This kind of behavior is totally unacceptable and has no place in football."

Fans clash at Stade Velodrome in Marseille.

It said a decision on the sanctions would be made "within the next few days," once evidence had been considered.

No action has been taken against England's Football Association, whose fans were also involved in the clashes on the third straight day of football-related violence in the port city. UEFA is responsible for incidents at match venues, but not in surrounding areas.

Dozens injured, 8 arrests

At least 35 people were injured Saturday, four of them seriously, said Mathieu Duroselle, a spokesman for Marseille police. The number included three officers who suffered slight injuries, he said.

Eight people were arrested, including British, Russian and French citizens.

The British government said in a statement Sunday that six British nationals were hospitalized and several others had received treatment.

"The UK Government is deeply concerned by the violence in Marseille last night, including reports that in some cases England fans were attacked by rival supporters," it said. "We condemn the violence and urge calm on all sides."

It said it welcomed UEFA's launching of an investigation into the violence at the stadium, and had offered to send additional British police to France ahead of England's next match, against Wales in Lens.

With French authorities, at the Ops Centre in Marseille Prefecture. Following up on injured. Shame actions of few spoil it for others. — Julian King (@JulianKingFCO) June 11, 2016

FIFA, the sport's international governing body, also released a statement condemning the violence.

The organization said it was "wholly unacceptable to see such shameful scenes around football matches perpetrated by a minority of idiotic troublemakers, who have nothing to do with football and its true fans."

Clashes in the stadium following the England-Russia match.

Violent scenes

The specter of hooliganism returned to the high-profile tournament Saturday as rival fans brawled before and after the match.

The fixture, anticipated by fans as the marquee game of the second day of Euro 2016, ended in a 1-1 tie.

In chaotic scenes involving hundreds of fans, throngs of rival supporters rushed at one another, hurling bottles, chairs and other objects, and forcing police in riot gear to fire tear gas in response.

Fans skirmish ahead of the match in the French port city of Marseille on Saturday.

Distressing footage emerged of men kicking and stomping on another person lying on the street in broad daylight, as the rivalry turned violent prior to kick-off.

Then, at the end of the game, Russian fans charged at the section of the stadium containing England supporters and more chaos ensued. Smoke filled the streets as panicked fans fled.

Rebekah Vardy, wife of English striker Jamie Vardy, was critical of the crowd policing.

"That has to be up there with the worst experience EVER at an away game! Teargassed for no reason, caged and treated like animals! Shocking!" she wrote on her Twitter account, calling the scenes "horrific and uncalled for."

That has to be up there with the worst experience EVER at an away game! Teargassed for no reason, caged and treated like animals! Shocking! — Rebekah Vardy (@RebekahVardy) June 11, 2016

In a statement, UEFA acknowledged "segregation issues" at the stadium and promised to "implement corrective measures to strengthen the deployment of security personnel at stadiums, in close collaboration with local authorities."

England fans clash with police ahead of the match.

France deploys extra security

Both teams have reputations for having hooligan elements among their support base, and officials had identified Saturday's match as a potential flashpoint.

Photos: Are these young men the Ballon d'Or winners of the future? Photos: Are these young men the Ballon d'Or winners of the future? Renato Sanches, 18 -- Portugal and Bayern Munich – He's one of the most expensive teenagers in history after opting to join German champion Bayern for an initial fee of €35 million ($40 million) on a five-year deal.

One of Europe's hottest prospects, the dreadlocked 18-year-old can tackle, shoot, chase down lost causes and is extremely fit -- so is it any wonder he received multiple offers from across Europe?

All the interest came despite the central midfielder only making his debut for Benfica, who he joined as a nine-year-old, in October 2015. A month later, the Lisbon-born youngster was starting in the Champions League -- and by the end of the season, he had his first league winner's medal as well.

In March, Sanches -- who has Cape Verdean roots -- made his Portugal debut. It came days after he joined Bayern, which described him as "dynamic, good tackler and technically skilled" upon his signing. It's been quite a season. Hide Caption 1 of 8 Photos: Are these young men the Ballon d'Or winners of the future? Dele Alli, 20 -- England and Tottenham Hotspur – Alli shone during his debut English Premier League campaign, impressing with his ability while also becoming the youngest midfielder to hit 10 goals in a season. Add his nine assists to that and it's easy to understand why the lanky midfielder was named PFA Young Player of the Year.

He was key to Tottenham's best Premier League finish in years. His three-match ban at the end of the season resulted in Spurs failing to win a game and -- having been challenging for the title with him -- dropping from second place to third.

With a fine first touch, eye for a pass and a ghost-like ability to drift into scoring positions, Alli has been earning rich acclaim.

Alex Ferguson compared him to Paul Gascoigne, a hero of England's 1990 World Cup team, while Liverpool legend Steven Gerrard said Alli is better at his age than he was.

He arrived at Tottenham from lower-league MK Dons with a goalscoring reputation and, after a slow start, the goals began to flow -- including a stunning swivel-and-volley against Crystal Palace.

England fans will hope Alli can continue his near-telepathic understanding with club and country teammate Harry Kane, who benefited from seven of Alli's nine assists this year. Hide Caption 2 of 8 Photos: Are these young men the Ballon d'Or winners of the future? Victor Lindelöf, 21 -- Sweden and Benfica – Type Victor Lindelof into Google and you'll see a list of the world's biggest clubs linked with him: Real Madrid, Barcelona and Manchester United lead the way.

The level of interest is surprising given the 21-year-old central defender only made his debut for Benfica, who he joined in 2011, in January.

He may have started the season as fourth choice but he took his chance with both hands when it arrived.

Nicknamed the "Iceman" because of his seemingly-unflappable personality, the tall shaven-headed youngster was so impressive that he made his international debut in March.

He started friendlies against Turkey and Czech Republic that month, and is set to be a Sweden regular for years to come. Hide Caption 3 of 8 Photos: Are these young men the Ballon d'Or winners of the future? Arkadiusz Milik, 22 -- Poland and Ajax – Since arriving at Ajax Amsterdam in 2014, the tall striker has steadily improved -- from 11 goals in 21 games in his debut season to 21 in 31 during the 2015-16 campaign.

A sign of how highly the Dutch club rated him is that Ajax handed Milik the No. 9 shirt for last season shortly after his original loan move from Bayer Leverkusen became permanent.

A keen dribbler who can score from distance with his trusty left foot, Milik endeared himself to the Ajax faithful when he plundered six goals in a cup tie.

At international level, he has also hit the ground running -- with 10 goals from 24 games after making his debut in 2012. Perhaps the most enjoyable came as Poland beat Germany, then recently-crowned as world champion, for the first time, winning 2-0 in a Euro 2016 qualifier in October 2014.

That was one of six goals Milik, who has formed a good partnership with Robert Lewandowski up front, scored in nine Euro 2016 qualifiers.

He has been linked with English Premier League champion Leicester and Spain's five-time Europa League winner Sevilla. Hide Caption 4 of 8 Photos: Are these young men the Ballon d'Or winners of the future? Leroy Sane, 20 -- Germany and Schalke 04 – His mother was an Olympic bronze medalist in gymnastics from Germany while his father played football for Senegal. Sane has managed to neatly combine the two, becoming a Germany football international.

The right winger made his debut for Schalke 04, where he came up through the ranks, in 2014. His rise has been such that then Bayern coach Pep Guardiola praised his "great talent" ahead of the teams' meeting last November.

That month Sane made his Germany debut in a 2-0 defeat against France in an international overshadowed by terror attacks. National coach Joachim Loew highlighted the youngster's pace, technique and desire to take on opponents.

A dribbler who can break a game with a bit of magic, the nimble Sane -- who already has a Champions League goal at the Bernabeu to his name -- can play anywhere behind the striker.

He may be tied to Schalke until 2019, but that isn't stopping an avalanche of media interest about a possible move to Bayern, with Guardiola's Manchester City and Jose Mourinho's Manchester United also heavily linked.

Hide Caption 5 of 8 Photos: Are these young men the Ballon d'Or winners of the future? Breel Embolo, 19 -- Switzerland and Basel – He's not even 20 but Embolo has already won three Swiss league titles. Since scoring five minutes into his league debut in March 2014, the burly striker has plundered 20 goals in 58 games.

Both physically and technically strong, Embolo has explosive pace and can drop into central midfield if needs be, as he has already proven both domestically and in the Champions League.

Just a year on from his Basel debut, he was in the senior Switzerland team -- a disappointment for the land of his birth, Cameroon, which had hoped to lure him instead.

Embolo is likely to start the Euros on the bench but should feature in all three group games.

With Basel having turned down a January offer from Wolfsburg, the youngster is now being linked with Tottenham -- perhaps a smart move from the London club, as the player's stock is set to rise in France. Hide Caption 6 of 8 Photos: Are these young men the Ballon d'Or winners of the future? Pavel Kaderabek, 24 -- Czech Republic and Hoffenheim – Will Euro 2016 be the tournament that catapults this marauding right-back into the limelight?

Once a laboring winger, Kaderabek's fortunes were turned on their head when he was repositioned to defense. Having failed to stand out in midfield, he immediately shone in his new role -- ending his maiden season at right-back for Sparta Prague with five goals, 10 assists and a league and cup double to his name.

The following season, 2014-15, Kaderabek was voted the Czech league's best player even though Sparta's trophy cabinet lay bare. He was soon on his way to Germany's Hoffenheim, where his contract expires in 2019.

He has goals in his locker -- having scored in a Euro 2016 qualifier against Iceland -- and allies super fitness with good pace.

That said, the Czechs like to play attacking football under coach Pavel Vrba, meaning the stocky Kaderabek will have his work cut out in France shuffling up and down the flank. Hide Caption 7 of 8 Photos: Are these young men the Ballon d'Or winners of the future? Oguzhan Ozyakup, 23 -- Turkey and Besiktas – An attacking central midfielder who has been compared to Mesut Ozil, Ozyakup actually began his career at the German's current club Arsenal -- only to leave after making one solitary appearance in an English League Cup tie in 2011.

But that wasn't for any lack of talent.

Arsenal manager Arsene Wenger said Ozyakup was "top quality" and "technically very good," while also praising his "very good stamina" and "good final pass."

However, the Frenchman said the player had "too much competition" for a first-team place. Instead, Netherlands-born Ozyakup moved to Turkey in 2012, where his Besiktas coach Slaven Bilic made the Ozil comparison both on account of his ability and physique.

Key to Besiktas winning the 2015-16 league title, the former Dutch youth international changed national allegiance. So it was with no little irony that his first international goal came against Holland in a Euro 2016 qualifier. Hide Caption 8 of 8

At the last UEFA European Championship, played in Poland in 2012, Russia was penalized for the poor behavior of traveling supporters -- including violent disorder and the racial abuse of a black player from Czech Republic

France's Interior Ministry classified Saturday's match as "at risk" and police sent in reinforcements, with about 1,000 police officers deployed to provide security, according to Marseille police spokesman Duroselle.

The French Interior Ministry had previously announced international moves to keep hooligans out of the country during the tournament, which is also being held under the shadow of a potential terrorist threat.

At the request of French authorities, Britain retained the passports of thousands of people considered hooligans, stopping them from coming to France during the competition.

"There have been 3,000 entry denials by the Minister of Interior, based on lists of people who are banned from stadiums in different countries participating in the competition, or individuals likely to disrupt the order in national territory," the Interior Ministry said.

Two hundred foreign police officers had also traveled to France to help prevent any outbreaks of violence during the tournament.

Bars closed early

Other measures to prevent violence included bars closing early in the Vieux-Port area in Marseille -- the same area clashes broke out Thursday and Friday nights among football fans.

Photos: Europe's David gets ready for Goliath Photos: Europe's David gets ready for Goliath Entering Euro 2016 with team comprised of a population of just 330,000, Iceland became the smallest country to ever qualify for a major tournament. Hide Caption 1 of 12 Photos: Europe's David gets ready for Goliath Iceland's national football team's coach Lars Lagerback, who formerly coached Sweden and Nigeria to the World Cup finals, has added a great deal of professionalism to the side, his players say. Hide Caption 2 of 12 Photos: Europe's David gets ready for Goliath Along with plying his trade as the joint head coach of the team, Heimir Hallgrimsson still practices his first vocation -- dentistry. Hide Caption 3 of 12 Photos: Europe's David gets ready for Goliath Star striker Eidur Gudjohnsen (left, formerly with Bolton), celebrates a goal with Craig Davies in 2015. Gudjohnsen, 37, is the team's elder statesmen, as well as it's most famous international player. The forward won titles with Chelsea and Barcelona. Hide Caption 4 of 12 Photos: Europe's David gets ready for Goliath Iceland's center back Kari Arnason, who plays for Malmo in the Swedish league, says becoming a professional footballer was never a realistic dream for him growing up. Hide Caption 5 of 12 Photos: Europe's David gets ready for Goliath Forward Jon Dadi Bodvarsson (right) takes on a Turkish defender during the Euro 2016 qualifier in September 2014. Iceland won the match 3-0, giving them a the perfect start to what would become a fairytale qualifying campaign. Hide Caption 6 of 12 Photos: Europe's David gets ready for Goliath Kolbeinn Sigthorsson, who plays for Nantes in the top tier of the French league, has scored 19 goals for his country. Hide Caption 7 of 12 Photos: Europe's David gets ready for Goliath Goalkeeper Thor Hannes Halldorsson played behind a defence which conceded just six goals in 10 qualifying matches. Hide Caption 8 of 12 Photos: Europe's David gets ready for Goliath Defender Ari Freyr Skulason battles Dutch forward Arjen Robben. Iceland won both matches against the Netherlands, traditionally one of world football's superpowers. Those defeats contributed to the Dutch missing out on qualification for the tournament in France. Hide Caption 9 of 12 Photos: Europe's David gets ready for Goliath Gylfi Sigurdsson of Swansea City is one of the most important players for Iceland, and its only England's Premiers League player. Hide Caption 10 of 12 Photos: Europe's David gets ready for Goliath Defender Ari Freyr Skulason (in blue) in action during Iceland's opening qualifying match against Turkey. Iceland -- a country of 330,000 -- won the match 3-0 against Turkey, which boasts a population of nearly 75 million. Hide Caption 11 of 12 Photos: Europe's David gets ready for Goliath Iceland's fans slowly grew in numbers as belief as their qualifying campaign unfolded. More than 8% of the entire country applied for Euro 2016 tickets. Hide Caption 12 of 12

Multiple bars in the area said they shut their doors at 8 p.m. local time Saturday.

Among the bars is O'Malley's, an Irish pub that usually closes at 11 p.m.

CNN law enforcement analyst Steve Moore said that violence among fans had become less of a feature of football tournaments in recent years, as the game's administrators looked to stamp it out of the sport.

The scenes in Marseille, he said, "were broadly in line with what we would have expected about 15 years ago."

Skirmishes were also reported Saturday night in the French city of Nice ahead of Sunday's match between Poland and Northern Ireland.

The situation in Paris for Sunday's game between Croatia and Turkey was largely calm, according to Paris police spokeswoman Johanna Primevert. She said there were isolated incidents of local troublemakers throwing projectiles near the Parc Des Princes stadium in an attempt to instigate visiting fans, but police swiftly brought the situation under control.