FIFA has yet to officially announce whether it is investigating Paul Pogba's world-record transfer from Juventus.
Several national newspapers claim football's world governing body has asked United for clarification on all aspects of Pogba's £89million move to the club last summer.
It is believed to be linked to claims that agent Mino Raiola pocketed £ 41million from the deal that took the France international to Old Trafford.
Although FIFA has yet to confirm whether it is looking into the figures, United appear relaxed about the situation.
A spokesman said on Tuesday : 'We don't comment on contracts.
"FIFA have had the documents since the transfer was completed last August.''
France international Pogba is in his second spell at United, having previously left Old Trafford in 2012 to move to Juve.
He has been a regular feature of the United midfield this season, scoring seven goals in all competitions for Jose Mourinho's side.
Pogba returned from a muscle complaint to impress in last week's Europa League semi-final first leg match away to Celta Vigo, which ended in a 1-0 win for United.
Source: PA
