Story highlights FIFA was cleared of corruption allegations by an internal investigation conducted by an American

But the FBI has intensified its own investigation of international soccer's governing body

The investigation centers on whether corruption led to the selection of Qatar to host the 2022 World Cup

U.S. investigators are stepping up the pace of a corruption investigation into senior leaders of FIFA, even as the world soccer body is giving itself a clean bill of health, according to U.S. law enforcement officials.

The FIFA ethics committee announced Thursday that it was closing its investigation into alleged corruption in the 2018 and 2022 bidding process that awarded the World Cup to Russia and Qatar, respectively.

FIFA said its investigation found no corruption and has no reason to reopen the bidding process.

But the FBI, which is leading the U.S. probe, isn't ready to do the same. Investigators are moving ahead with their probe, which could result in charges against senior FIFA officials, the U.S. law enforcement officials said.

FBI agents based in New York are moving ahead with their 3-year-old investigation, which will likely benefit from the findings of a former U.S. prosecutor, Michael Garcia, who was hired by FIFA to do an internal probe. The FBI plans to seek access to Garcia's report, which FIFA hasn't yet released.

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The FBI declined to offer an official comment.

Garcia on Thursday distanced himself from the FIFA ethics announcement, saying: "Today's decision by the Chairman of the Adjudicatory Chamber contains numerous materially incomplete and erroneous representations of the facts and conclusions detailed in the Investigatory Chamber's report. I intend to appeal this decision to the FIFA Appeal Committee."

A U.S. law enforcement official said the probe is looking at a variety of alleged corruption issues, including the 2018 and 2022 bidding process.

The FBI investigation includes the cooperation of a former top FIFA official who has provided documents and recordings of meetings with colleagues, law enforcement officials said.

The New York Daily news, which reported on the cooperation of former FIFA official Chuck Blazer, quoted Blazer as saying: "I just can't talk about that."

FIFA has long been dogged by allegations of corruption. In 2011, the FIFA banned for life Mohamed bin Hammam, a Qatari member of its top governing body, for ethics violations.

The organization says it is planning unspecific improvements in the way it conducts World Cup bids.