Christopher Steele, who wrote reports on compromising material Russian operatives allegedly had collected on U.S. President-elect Donald Trump, is a former officer in Britain's Secret Intelligence Service, Reuters reports citing people familiar with his career.

Former British intelligence officials said Steele spent years under diplomatic cover working for the agency, also known as MI-6, in Russia and Paris and at the Foreign and Commonwealth Office in London.

After he left the spy service, Steele supplied the U.S. Federal Bureau of Investigation (FBI) with information on corruption at FIFA, international soccer's governing body.

It was his work on corruption in international soccer that lent credence to his reporting on Trump's entanglements in Russia, U.S. officials said on Wednesday.

Emails seen by Reuters indicate that, in the summer of 2010, members of a New York-based FBI squad assigned to investigate "Eurasian Organized Crime" met Steele in London to discuss allegations of possible corruption in FIFA, the Swiss-based body that also organizes the World Cup tournament.

People familiar with Steele's activities said his British-based company, Orbis Business Intelligence, was hired by the Football Association, Britain's domestic soccer governing body, to investigate FIFA. At the time, the Football Association was hoping to host the 2018 or 2022 World Cups. British corporate records show that Orbis was formed in March 2009.

Amid a swirl of corruption allegations, the 2018 World Cup was awarded to Moscow and Qatar was chosen to host the 2022 competition.

The FBI squad whose members met Steele subsequently opened a major investigation into alleged soccer corruption that led to dozens of U.S. indictments, including those of prominent international soccer officials.

Senior FIFA officials, including long-time president Sepp Blatter, were forced to resign.