(CNN) The US Department of Justice (DOJ) isn't letting up on its investigation into corruption in soccer .

Its latest indictment filed in US District Court in March was made public this week , alleging that bribes were accepted by top officials ahead of the votes that allocated Russia and Qatar as respective hosts of the 2018 and 2022 FIFA World Cups.

Both countries were granted host status in 2010 -- Russia ahead of a bid from England and Qatar ahead of the US.

Qatari officials "strongly deny" the allegations, while Russia "categorically rejects" that bribes were accepted.

"Despite years of false claims, evidence has never been produced to demonstrate that Qatar won the rights to host the FIFA World Cup 2022 unethically or by means that contravened FIFA's strict bidding rules," said a statement sent to CNN by Qatar's Supreme Committee for Delivery & Legacy (SC), which oversees planning of the 2022 World Cup.

"The SC maintains that it strictly adhered to all rules and regulations for the 2018/2022 FIFA World Cup bidding process and any claim to the contrary is baseless and will be fiercely contested."

Photos: Qatar 2022 Khalifa International Stadium – The Khalifa International Stadium was the first of the Qatar 2022 World Cup venues to be completed. Hide Caption 1 of 14 Photos: Qatar 2022 Khalifa International Stadium – It officially opened on May 19, 2017, and can hold 48,000 fans after being expanded for the World Cup. Hide Caption 2 of 14 Photos: Qatar 2022 Khalifa International Stadium – Initially opened in 1976, the stadium is situated close to Doha's impressive Aspire Zone and has undergone two reconstructions, first in 2005 and then in 2017. Hide Caption 3 of 14 Photos: Qatar 2022 Al Wakrah Stadium – An artist's rendering of the Al Wakrah stadium in Qatar. Hide Caption 4 of 14 Photos: Qatar 2022 Al Wakrah Stadium – Situated a short distance outside Doha, the Al-Wakrah Stadium was designed by Zaha Hadid Architects and will have a capacity of 40,000. It will also host games up until the World Cup quarterfinals. Hide Caption 5 of 14 Photos: Qatar 2022 Qatar Foundation Stadium – The Qatar Foundation Stadium in Doha's Education City will have an initial capacity of 40,000. Hide Caption 6 of 14 Photos: Qatar 2022 Qatar Foundation Stadium – But that will be reduced to 20,000 after the tournament, with half the seats removed and donated to build stadiums in developing countries. Hide Caption 7 of 14 Photos: Qatar 2022 Al Bayt Stadium – The Al Bayt Stadium will be built in the city of Al Khor to the north of Doha and have a capacity of 60,000. Hide Caption 8 of 14 Photos: Qatar 2022 Al Bayt Stadium – An artist's impression of the exterior of the Al Bayt Stadium. Hide Caption 9 of 14 Photos: Qatar 2022 Al Bayt Stadium – The stadium design, which depicts a giant tent structure, honors Qatar's past and present, according to Qatar's Supreme Committee for Delivery and Legacy. Hide Caption 10 of 14 Photos: Qatar 2022 Al Thumama Stadium – The 40,000-seat Al Thumama Stadium will host matches up to the quarterfinals of the 2022 World Cup. The venue's design represents the gahfiya, a traditional woven cap worn by males across the Arab world. Hide Caption 11 of 14 Photos: Qatar 2022 Al Rayyan Stadium – The Al Rayyan Stadium will be built on the site of the existing Ahmed Bin Ali Stadium in Al Rayyan just outside Doha.

Hide Caption 12 of 14 Photos: Qatar 2022 Al Rayyan Stadium – An artists' impression of the Al Rayyan Stadium which will host matches up until the quarterfinal stage of the tournament. Hide Caption 13 of 14 Photos: Qatar 2022 The Lusail Iconic Stadium just outside Doha is slated to host the opening and closing matches of the 2022 World Cup. It's also at the center of the Lusail City project which will eventually be home to more than 200,000 people, according to Qatar's Supreme Committee for Delivery and Legacy. Hide Caption 14 of 14

Qatar has faced strong criticism since being awarded the right to host the World Cup, including for its human rights record and use of migrant workers to construct new stadiums. Qatari officials have consistently defended the country's record on both issues.

Russian officials also deny the latest bribery claims.

"We have read media reports and we cannot understand what it is all about," said presidential spokesman Dmitry Peskov according to Russian news agency TASS

"Russia was granted the right to host the world championship on an absolutely legal basis and it has nothing to do with some kind of bribery, which we categorically reject."

The DOJ's long-standing probe into corruption within the sport saw 16 FIFA officials face criminal charges in 2015 , which included racketeering, money laundering and wire fraud.

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A statement from FIFA said it "supports all investigations into alleged acts of criminal wrongdoing regarding either domestic or international football competitions and will continue to provide full cooperation to law enforcement officials investigating such matters.

"FIFA is closely following these investigations and all related developments in the legal processes ongoing in the United States and other parts of the world.

"It is important to point out that FIFA has itself been accorded victim status in the US criminal proceedings and senior FIFA officials are in regular contact with the US Department of Justice.

"Following the latest indictment, FIFA will ask the DOJ for further information on these matters.

"The FIFA Ethics Committee has already imposed sanctions, including life bans, on football officials mentioned in this process. So far as FIFA is concerned, should any acts of criminal wrongdoing by football officials be established, the individuals in question should be subject to penal sanctions."