Rafael Benitez to be handed £500m to improve Newcastle squad should Amanda Staveley complete takeover

Rafael Benitez will be handed £500m to improve his Newcastle United squad in the next two transfer windows if Amanda Staveley completes her takeover of the St James' Park club.

Staveley's PCP Capital Partners firm are ready to bid £300m to acquire the club from Mike Ashley, after the Sports Direct owner reaffirmed his desire to sell up last week.

Ashley has signed a confidentiality disclosure agreement with five different parties who are interested in buying Newcastle, but it is Staveley's potential bid which has been met with the greatest optimism.

She helped broker the takeover of Manchester City in 2008 and was part of a Dubai-led takeover bid to buy Liverpool. But according to The Express should a deal to acquire Newcastle be completed then a transfer kitty of half a billion pounds will be offered to Benitez.

Among the key criticisms of Ashley's tenure at the helm has been the lack of funds provided to each of the eight permanent managers to have worked for him. Benitez has been among them, having only spent £95m during his 19 months in charge during which time he has taken the club from the Championship into the Premier League's top seven.

Having once again declared his intention to sell – Ashley has twice seen attempts to offload Newcastle fall through – the sportswear tycoon wants a deal completed before the end of the year. But the complicated nature of the sales of football clubs means it may take months rather than weeks for Staveley or another party to complete the takeover.

Therefore it is uncertain when Benitez will have new funds available to invest in his squad. Last week it was suggested the Spaniard would have £150m to spend over the next two years but that figure has multiplied in recent days.

Latest reports indicated that the cash injection could mean Newcastle firm up their interest in re-signing Andros Townsend from Crystal Palace. A deal for the England winger fell through in the summer but Palace are keen to revive the move to finance the move for a striker.

Benitez has been coy over the benefits new owners would have to Newcastle's future, perhaps due to the manner in which previous takeover bids have failed – but the club's record goalscorer and former captain Alan Shearer says fresh investment will ensure they can dare to dream.

"I don't know the potential buyer Amanda Staveley, or what her plans are for the club, but I know what they should be," Shearer told The Sun. "They should be to back a world-class manager to the hilt. Because the club has one in Rafa Benitez.

"My fear is that if a takeover does not go through by the end of this season, he will be lost to Newcastle. Benitez has them up in seventh place. Imagine what he could be doing with some serious financial backing.

"All we have ever wanted is hope our club can challenge the very best, hope that they can win a trophy, hope that our dreams and desire for the club can be matched by those owning and running it."