Doubts about the feasibility of 'saving' London's Bart's Hospital as a specialist cardiac and cancer centre are growing less than 18 months after the high-profile decision was made.

In a letter to health secretary Frank Dobson, City and Hackney primary care group, which represents 56 GP practices, says it fears that no new money has been earmarked for the development.

Dismissing the current plan as 'entirely unaffordable', the PCG says it would be 'unjust to try to fund this out of the allocation we receive to provide basic health services for the poorest people in the country'.

PCG co-chair Clare Highton said local funds had already been raided to meet this year's nurses' pay award.

A spokesperson for Barts and the London trust said detailed plans for Bart's, including costs, will go to the trust board at its next meeting on 7 July.

East London and the City health authority has thrown its weight behind the trust's proposal.

However, the HA, which is£23m short of its national funding allocation, insists: 'Clearly any development would need to be affordable.'

Estimates of the extra costs of running two sites rather than one have been put at between£20m and£30m.