Ryan Giggs would be worth £2-billion in the modern transfer market, former Manchester United teammate Roy Keane outlandishly claimed.

Neymar made a £198m move from Barcelona to Paris Saint-Germain earlier this month, more than doubling the previous world-record fee.

With Everton buying Gylfi Sigurdsson from Swansea City for £45m, and Marko Arnautovic swapping Stoke City for West Ham in a £24m deal, ex-United captain Keane is bemused by the figures now involved.

The 46-year-old suggested his Old Trafford colleagues would be worth 10-figure sums if they were available on the current market.

“Ruud [van Nistelrooy] would be worth a billion. [David] Beckham, a billion. Giggsy, two billion,” said Keane.

“It’s mind-boggling, it really is. The figures out there now for players – it’s not the player’s fault, it’s the market, the market value of players.

“It’s mind-boggling – especially for the average players. If ever there’s a time to be a professional footballer, it’s now – average players are going for £35m. My goodness.

“The really brilliant players are going for big money. When average players are going for £30m-£40m, it does make you scratch your head.”

Asked what he would be worth, Keane jokingly replied “£3.75-million” – the amount United paid to sign him from Nottingham Forest in 1993.