Paris Saint-Germain’s transfer dealings are being investigated by the Union of European Football Associations (UEFA) under the body’s Financial Fair Play rules.
The French club, which has been owned by Qatar via its Qatar Sports Investments fund since 2011, shattered transfer fee records in August when it signed Neymar from Barcelona for €222 million (Dh968m).
PSG is also thought to be ready to pay up to €180 million in 2018 for teenager Kylian Mbappe, who is currently on loan to the Ligue 1 side from Monaco.
UEFA’s ‘break-even’ rules require clubs to balance spending with revenue over the course of three years.
PSG could pay up to €500 million for Brazilian striker Neymar between his transfer fee and €600,000 a week salary over his five-year contract.
The club, which is one of the wealthiest in the world since the Qatari takeover, accrued about €55m from selling players over the summer transfer period.
UEFA said it would be investigating PSG’s books over the coming months.
"The investigation will focus on the compliance of the club with the break-even requirement, particularly in light of its recent transfer activity," a statement by the body read.
"In the coming months, the Investigatory Chamber of the UEFA Club Financial Control Body will regularly meet in order to carefully evaluate all documentation pertaining to this case.
"UEFA considers Financial Fair Play to be a crucial governance mechanism which aims to ensure the financial sustainability of European Club Football."
PSG said it was “surprised” by the investigation as it had always operated with transparency.
"The club is surprised by this approach given that it has constantly kept Uefa informed about the financial impact of all players' operations carried out this summer, even though it wasn't obliged to do so. The club is very confident in its ability to demonstrate that it will fully comply with Financial Fair Play rules for the fiscal year 2017-2018,” PSG said in a statement.
"Deputy CEO Jean-Claude Blanc met with UEFA experts including Andrea Traverso, responsible for Uefa Financial Fair Play, for more than three hours on 23 August at Paris St-Germain's headquarters, where he demonstrated that the operations carried out with FC Barcelona and in progress at that time with AS Monaco followed the rules of Financial Fair Play for the financial year 2017-2018.
"On 31 August, the club's general management again had exchanges with UEFA Financial Fair Play management to provide a more detailed account of how the transaction with AS Monaco would be integrated into the club's accounts for this season, in terms of amortization and payroll, in compliance with French accounting standards.
"Furthermore, as for the summer of 2017, the club has already completed outgoing player transactions that helped improve club results by more than 104 million euros for the 2017/2018 season.
"The club also reminds, if necessary, that it has under contract many high valued players allowing the club to generate very significant capital gains in the next two transfer windows (January and June) of 2018."