NHS managers have been told to keep their hands off Wandsworth NHS's surplus after fears that it could be used to fill a £26.8m funding hole in Croydon.

Wandsworth NHS has prudently managed to accumulate a surplus of £16.7m but at a high level NHS meeting last week the spectre of it being handed over to its spendthrift neighbour was raised.

Wandsworth is now linked in a partnership with Croydon, Merton, Sutton, Kingston and Richmond but only Wandsworth has any money saved.

At the South West London Joint Boards meeting last week, the extent of debt run up by Croydon NHS was revealed.

NHS Croydon has not been able to produce any detailed evidence of how its debt managed to build up to such a level and who is responsible.

During Thursday's meeting, Steven Hickey, the vice-chair of NHS Wandsworth, said he was "very concerned" that Wandsworth might not be able to spend the savings it has accrued.

Tooting's MP and a health watchdog have since both condemned any attempt to use the money to bail out Croydon and on Tuesday a spokeman for NHS South West London denied it was planning to do this.

A spokesperson for NHS South West London said: “NHS Wandsworth surplus will not be used to bail out NHS Croydon’s deficit."

A spokesperson for NHS Wandsworth added: "The NHS Wandsworth Board has agreed to achieve a financial surplus of £16.7 million by the end of 2011/12.

"This funding will be carried forward for future investment in health care in Wandsworth in 2012/13 and beyond.

"We know that the financial challenge for the NHS is going to increase over the next few years.

"Increasing our surplus this year through careful management enables us to be better prepared for the challenges of future years."

One possible alternative solution is for the debt to be written off next year when GPs take over the management of NHS fundsand NHS trusts are disbanded.

Sadiq Khan, Tooting MP and shadow justive minister, said: "This development is extremely worrying, but hardly surprising given the costly, chaotic and rushed nature of the government’s NHS reorganisation.

“At a difficult time for the NHS, local health professionals, who have worked hard to deliver a first class service on budget, do not want to see their hard work go down the drain.

“The Government must ensure that their ideological reorganisation does not punish well-run NHS services, meaning local patients suffer.”

John Lister, of London Health Emergency, believes questions need to be asked not only about Croydon's use of the money but why Wandsworth has not invested it at a time when the NHS is being squeezed nationwide.

He said: "I think the message here to NHS Wandsworth is use it or lose it. Particularly at a time when the goverment has decided to bung everyone together in the clusters and essentially share the money around.

"Wandsworth's surplus should be spent on Wandsworth patients, rather than being snatched off them by health secretary Andrew Lansley.

"It does look terribly unfair but the Government has consciously decided to clump these organisations together.

"I guess the real question is why is Wandsworth running at a surplus? I am puzzled why £16m has not been spent on patients?"