Chuck Blazer was working undercover for the FBI for 18 months while still a member of Fifa’s executive committee, his plea agreement with US justice authorities revealed yesterday.

The 70-year-old struck a deal to become an informant to avoid a potential jail term of up to 75 years after pleading guilty to 10 charges, including bribery, money laundering and tax evasion.

His plea agreement has been made public and confirms he agreed to work undercover from December 2011.

The disclosure was revealed as Fifa expressed angry disappointment at the Nobel Peace Centre’s decision to sever its links with the world governing body.

Blazer and three others have pleaded guilty to football-related corruption, while another 14 people have been indicted.

These include seven Fifa officials arrested in Switzerland on May 27 who are contesting extradition to the United States.

The 19-page plea agreement says: “The defendant agrees to furnish to the office all documents and other material that may be relevant to this investigation and to participate in undercover activities pursuant to the specific instructions of law enforcement agents.”