Uefa have announced that they have opened a 'formal investigation' into Paris Saint-Germain after the French club spent over £200m on new transfers this summer.

The French club signed Neymar from Barcelona for £200m, smashing the previous world-record transfer fee by over £100m.

They followed up that signing by recruiting Kylian Mbappe from Monaco on transfer deadline day, initially on a season-long loan.

However, the agreement with Ligue 1 rivals Monaco includes an obligation to purchase the 18-year-old for £166m next summer.

They also signed Real Sociedad defender Yuri Berchiche in a £15m deal.

Uefa's Financial Fair Play (FFP) regulations were introduced by former president Michael Platini in an attempt to ensure that European clubs livewd within their means.

With the exception of a small loss (currently set at 5m Euros) spread over three seasons, a club's outgoings is supposed to match its incomings under the regulations. PSG have sold three players this summer, netting just £51m.

Neymar joined the club in a world-record £200m fee (Getty)

“The Chamber of Inquiry of the UEFA Club Financial Inspectorate opened a formal investigation into the Paris Saint-Germain as part of its ongoing monitoring of the clubs under the Fair Play Financial Regulation (FPF ),” Uefa said in a statement published on Friday afternoon, a day after the French transfer window closed.

“The investigation will focus on the club's compliance with the requirement of financial balance, particularly in light of its recent transfer activity.

“Over the next few months, the Investigation Chamber of the UEFA Club Financial Supervisory Body will meet regularly to carefully evaluate all documentation relating to this case.

“UEFA considers financial fair play to be an essential link in the governance of the club, ensuring the financial sustainability of European football.