Mike Ashley will only sell Newcastle to a buyer who has the financial muscle to invest heavily in the playing squad.

Ashley announced on Monday evening that he will accept structured payments for the Magpies.

Press Association Sport understands the reason for this is to allow a buyer to invest in players at the same time as meeting the overall asking price via instalments.

Sources have indicated that Ashley, who has spent much of his decade in charge at St James’ Park in conflict with large sections of the club’s support, will only do business with a buyer who is able to fund significant spending in a way he admitted recently he cannot do.

As a result, there is no hard and fast price tag. There has been speculation that Ashley is looking for anywhere between £300million and £450million before relinquishing control, but a potential buyer being able to demonstrate a willingness to take the club forward on and off the field would appear to be as important as the price.

Newcastle are understood to have signed non-disclosure agreements with four prospective buyers, all of whom are at similar stages in their ongoing interest with none having reached the stage of making a formal offer.

Amanda Staveley watched Newcastle's draw with Liverpool Amanda Staveley watched Newcastle’s draw with Liverpool (Owen Humphreys/PA)

In addition, Amanda Staveley, who played a key role in Sheikh Mansour’s takeover of Manchester City in 2008, caused great excitement on Tyneside last month when she was spotted among the crowd for the Magpies’ 1-1 Premier League draw at home to Liverpool.

Staveley, who is said to control around £28billion of Middle East money through PCP Capital Partners, is reportedly looking to invest in an English top-flight club and met club officials after the game. However, as yet there has been no expression of interest in Newcastle from that source.

There were claims during the summer that Newcastle were attracting interest from China, although nothing further has materialised, while it is understood America could yet prove a source of investment.

Lawyer Andrew Henderson, who has acted on behalf of Ashley’s businesses in the recent past, is the man charged with handling the sale, and it is understood Monday’s announcement has prompted a flurry of activity.

Henderson, a partner at Dentons, hopes to broker a deal by the end of the year with insiders insisting Ashley’s firm intention is to sell this time after aborting two earlier attempts.

Newcastle are ninth in the Premier League after Sunday’s 2-2 draw at Southampton, which cemented a positive start to life back in the division after promotion.

The riches available to English football’s big guns – the current broadcast deal is worth £5.14billion – are a huge pull, and the Magpies enjoy the added advantages of having world-renowned manager Rafael Benitez at the helm and 52,000-plus home crowds.

However, an ongoing HMRC investigation into allegations that the club abused the tax system may prove a complication.

Benitez cut a frustrated figure in both January and the summer as his transfer plans were severely limited by Ashley’s decision not to fund major transfer spending, something the Spaniard believed would be forthcoming.

Ashley paid £134.4million for the club back in 2007 and has since made interest free loans totalling £129million, and his reluctance to commit further funds fuelled the rumours that he was ready to sell.