UEFA has opened a formal investigation into Paris Saint-Germain as part of its monitoring of clubs under Financial Fair Play (FFP) regulations, European football's governing body has announced.
It follows a world record €222 million transfer of Neymar from Barcelona and a reported €180m deal for Kylian Mbappe, star striker for Ligue 1 rivals Monaco, following his season-long loan deal this season.
Reports in Spain had suggested that both Barcelona and Real Madrid - whom were long considered the frontrunners to sign Mbappe - had complained to UEFA about PSG's conduct this summer.
Following the closure of the transfer window in France on Thursday and confirmation of Mbappe's switch to Parc des Princes, it took less than 24 hours for UEFA to announce it would be launching an investigation into the French club.
"The Investigatory Chamber of the UEFA Club Financial Control Body has opened a formal investigation into Paris Saint-Germain as part of its ongoing monitoring of clubs under Financial Fair Play (FFP) regulations'" UEFA stated on Friday in a press release.
"The investigation will focus on the compliance of the club with the break-even requirement, particularly in light of its recent transfer activity.
"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.
"UEFA will make no further comments on this matter while the investigation is ongoing."
While Mbappe and Neymar arrived, Serge Aurier and Blaise Matuidi were among the departures, but eyebrows were raised across Europe at whether PSG were following FFP rules with their unprecedented player expenditure.
While the investigation gets under way behind closed doors at UEFA, PSG will compete in the 2017-18 Champions League group stage against Bayern Munich, Anderlecht and Celtic.