FIFA has asked Manchester United for information about Paul Pogba's world record transfer from Juventus, following leaks which claimed to give details about the huge deal, a spokesman for the governing body said on Tuesday.
France international midfielder Pogba rejoined United for £89m (€105m) in August.
Extracts from a book, 'The Football Leaks: The Dirty Business of Football', published in this week, included a breakdown of the fee and were reproduced in media reports on Tuesday.
The book claimed that Pogba earns around £165,000-a-week and will receive a £3.4m loyalty payment each year starting from 2018.
As part of the deal which took Pogba to Old Trafford, his agent Mino Raiola is expected to earn a staggering £41million.
Raiola also represents United players Zlatan Ibrahimovic and Henrikh Mkhitaryan.
A United spokesman said: "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.