Football Association chairman Greg Clarke was asked to explain why allegations made against Neil Warnock were not followed up during an MPs' hearing into football governance.
Allegations that Warnock was "crooked" and was "ruining the game" were made by Crystal Palace midfielder Jason Puncheon in 2014 on Twitter and quickly deleted.
They were repeated in Westminster today by Damian Collins, the chairman-elect of the Culture, Media and Sport Committee.
Collins, the Conservative MP for Folkstone and Hythe, was questioning FA chairman Clarke about the governing body's attempts to investigate possible wrongdoing in the game and cited Puncheon's outburst as an example of an allegation that was not pursued.
In fact, Puncheon was fined £15,000 by the FA for bringing the game into disrepute and warned about his conduct.
Using parliamentary privilege, which gives MPs and witnesses protection for libel laws, Collins said: "The tweets have been deleted but for the benefit of the committee they are still available online, although they're not on his Twitter account.
"(Puncheon) said: 'What I won't accept is an opinion from a man who's crooked and ruining the game.
"'Neil Warnock, the man who signs players, gives them extra wages and appearance bonuses to make sure that they pay him to get into the team or on the bench.
"'The fact he could even talk about training is shocking, he was never there."'
Puncheon was reacting to a comment Warnock, who has managed 15 different clubs in a 37-year career, made as a pundit when the Palace player missed a penalty in a 2-0 defeat by Spurs.
Warnock, who had signed Puncheon on loan in 2011 when he was manager of QPR, told talkSPORT there was "no way I would've trusted him with a penalty" because he lacked a cool head under pressure.
The 67-year-old veteran manager, who took over at Cardiff earlier this month, was reunited with Puncheon at Palace later that year and said they resolved their differences. He had previously denied any wrongdoing and threatened legal action.
Clarke, who has only been FA chairman for five weeks, told Collins he did not know if the FA investigated Puncheon's claims about Warnock but suggested it certainly should have done so.
"I think it would be pretty poor if someone has gone public and they don't have any contact from the FA asking why have they made this allegation," said Clarke.
Robert Sullivan, the FA's director of strategy, was sitting alongside Clarke and he said: "Where the line is difficult to draw is bringing forward real evidence that can actually be used to take an investigation forward.
"There are comments made on social media and there is actual hard evidence that the investigators can actually use to bring forward a case and a charge."
Clarke explained that this was a common problem for the FA's 33-strong team of compliance officers and investigators, and denied the failure to successfully prosecute charges was a result of any lack of interest in tackling corruption.
"T here's a surfeit of people who say Fred or Mary is a villain. You then talk to Fred or Mary and they deny it and there's no third-party corroboration, no paper trail.
"So we focus on the cases where we can find that evidence."
In a series of pointed exchanges with Collins and other members of the panel, Clarke asked for more time to force through the changes he wants the FA to make to its anti-corruption team, development work and governance structure.
The former Leicester and Football League chairman admitted that he would like to stop unscrupulous agents from taking so much money from the game but said the FA needed more help from FIFA and UEFA, as it was a cross-border issue.
Clarke also suggested he would like a stronger 'owners and directors test' for potential investors in clubs but the Rehabilitation of Offenders Act made that difficult to enforce.
When asked by Collins if he would like parliament to change the law, Clarke said "maybe" but only after he undertakes a full review of the current situation.
Source: PA
