Jiminez was responsible for player recruitment at St James's Park, having helped bring the likes of Fabricio Coloccini and Jonas Gutierrez to Tyneside.

But the Londoner was at the centre of the storm last month which resulted in Kevin Keegan walking away from his position as manager due to the lack of control over transfers.

The fall-out from that bombshell saw United fans protest against the "Cockney Mafia" in charge of the club, and owner Mike Ashley quickly put the club up for sale.

And while any potential purchase of the club looks set to drag on until at least the new year, Jiminez has decided there was no longer any point in wasting time flying around the world to scout players that may never pull on a black and white shirt.

With the sale of the club in limbo, it would be a major surprise if United were to spend any money in the January transfer window.

A source close to Jimenez revealed: "Tony just felt there was no point in continuing his position.

"He knows that the club could be sold, and even it is not, there is the possibility that the club won't spend money in January with the future so uncertain.

"He is expected to take up another role soon because he wants to continue working in the game."

As well as Argentinian duo Gutierrez and Coloccini, Jiminez was also involved in bringing Sebastien Bassong, Nacho Gonzalez and Xisco to Newcastle.

The majority of his contacts were overseas, particularly in Spain, with Gutierrez, Coloccini, Gonzalez and Xisco all arriving from La Liga.

Jiminez also played a key role in appointing Dennis Wise as director of football, but despite his close pal's decision to quit, there is no sign that Wise will follow him out of the door before the club is sold.

The global financial crisis has meant that buyers have so far been slow to meet the reported asking price of £250-300m that Ashley has slapped on United, with an October 17 deadline having been put on serious bids.