The NFL is adding yet another London game next year in what may be a sign the league is becoming more serious about placing a franchise in the city. On Fridaythe NFL announced they will play four games in the city, but did not name the stadiums or teams, saying they will make a formal announcement on Tuesday.

Adding the fourth game is a significant development in the NFL’s attempts to build a European market because it shows it is still exploring the city’s potential as a franchise site. In February, a top league official told the Guardian the NFL wants to gradually move toward playing the equivalent of a team’s eight-game home schedule in London to see if the interest from UK fans is there to support a team full time. Moving from the three games played this year to half of a season’s slate seems like a far bigger commitment than going from two games to three, which the league did before the 2014 season.

London has always been a priority of the league commissioner, Roger Goodell, who has pushed the experiment since he was appointed in 2006. League officials have long worried that while the NFL is the most-lucrative sports league in the world, the bulk of their reach is limited to North America, capping their opportunity to reach international markets the way the NBA, NHL and Major League Baseball have. As long as American television networks are paying huge sums for rights fees the league could still dominate without having to reach too far overseas. But this year the NFL TV ratings have dipped, meaning the need to grow internationally might be greater.

NFL weekend predictions: Cowboys to seal NFC East title against Giants Read more

The timing for a real push into London might be right for other reasons, too. For several years, league officials said they needed to place a team in Los Angeles before they could make a commitment to the UK. They partially resolved this issue by allowing the St Louis Rams to move back to the city they abandoned in 1995. Two other franchises, the Oakland Raiders and San Diego Chargers, are manoeuvring to join the Rams – with a Chargers move looking more likely. But even with that uncertainty, the NFL has indicated that they see Los Angeles as mostly complete.

There was some question that the NFL might be losing interest in London when they scheduled a game in Mexico City this season. They will also play one in China in 2018. But league officials said when the Mexico City game was announced that a team in the UK remained a goal.

“It’s not dead at all,” the Kansas City Chiefs chief executive, Clark Hunt, the head of the league’s international committee, told the Guardian in February, when asked about a permanent franchise in London.

On Fridaythat sentiment was echoed by Goodell. “We continue to be incredibly excited by the passion and love for the NFL shown by our millions of UK fans,” Goodell said in a statement. “London is an amazing city. We have had tremendous support from our fans, from [the mayor, Sadiq] Khan and government leaders and business partners and we are looking forward to taking the next step in the UK by playing four games in London next season.”

One of the biggest challenges the league has had in scheduling London games is finding enough teams willing to give up home games to play there. The Jacksonville Jaguars have a multiyear commitment to London and the NFL has a willing partner in the Rams who are playing in a temporary home the next two years, but the fact it was able to schedule four games appears to show there is a league-wide effort to see if London is a viable full-time NFL city.