London (AFP) – Former Manchester United star Roy Keane has slammed the “mind-boggling” spending of clubs paying huge fees for “average” players in a historically frenzied transfer window.

Keane, who now works as assistant to Republic of Ireland coach Martin O’Neill, has been shocked by some of the sums paid by Europe’s top clubs since the end of last season.

French giants Paris Saint-Germain have led the way, forking out a staggering £200 million (222mn euros, $263.5mn) for Neymar and preparing to invest heavily once again in Monaco’s Kylian Mbappe.

In the Premier League, the spree has set a new record for a single window as the 20 top tier clubs splashed out over £1.18 billion.

Manchester City splurged over £200 million, while 12 teams broke their transfer records.

Keane is astonished that players he regards as mediocre are being given lavish contracts after making big-money moves.

“It’s mind-boggling, the figures that are out there – especially for the average players. If ever there was a time to be a professional player it’s now. Average players are going for £35 million. My goodness,” Keane said on Tuesday.

“I don’t really analyse it too much, but that’s the market place at the moment. There aren’t many top players out there. The really big players are going for big money and it’s filtering down now.

“When average players are going for £30-40million, it does make you scratch your head. But if the clubs are prepared to pay that, then it’s not the players’ fault.”

Keane played alongside stars like David Beckham Paul Scholes, Ryan Giggs and Ruud van Nistelrooy, as well as Cristiano Ronaldo, who cost Real Madrid £80 million when he left Old Trafford eight years ago.

Asked what Van Nistelrooy would cost now, the 46-year-old replied: “Ruud would certainly be worth in the market now probably a billion.”

“David Beckham?”. “A billion.” “Ryan Giggs?” “Two billion.”

Asked further how much he himself might cost nowadays, Keane was more modest and referenced the then British record fee United boss Alex Ferguson paid to sign him from Nottingham Forest in 1993.

“£3.75 million, I think,” he said with a smile.