Conflict between the NHS Confederation and the Local Government Association over how care trusts will be run reignited this week, when MPs discussed the new bodies.

As scant detail of care trusts' governance arrangements emerged from the Commons standing committee debate on the Health and Social Care Bill, the LGA reiterated 'grave concerns' that it had raised in a letter to health secretary Alan Milburn last week. The letter was also signed by the Association of Directors of Social Services, Help the Aged, Age Concern and Unison.

The LGA, which has been seeking equal representation between the NHS and local authorities on care trust boards, reacted sharply to health minister John Hutton's statement to the standing committee that 'the primary care trust will be the building block and the foundation into which the local authority social services - or whatever body - will be incorporated'.

The detail of governance arrangements would be dealt with in guidance, Mr Hutton repeatedly told MPs. 'It would be a mistake to adopt a one-size-fits-all straitjacket about governance arrangements.'

An LGA spokeswoman said: 'If There is not going to be new governance arrangements, we can't be equal partners.'

She raised the prospect that councils might not want to participate in care trusts on this basis. 'If It is essentially a health body with social services bolted on, where will be the incentive for local authorities to get involved?'

But the NHS Confederation hit back, with a letter to Mr Hutton, apparently endorsing the minister's position. 'We think it is very important that local discussions leading to an application for care trust status can include debate about the most appropriate governance arrangements, ' chief executive Stephen Thornton said.

'The way forward is to use the PCT governance guidance as a model, allowing local discretion to build up a board most appropriate to the range and scale of services commissioned and provided.'

He added that 'decisions about numbers' of local authority representatives on care trust boards 'should be left to local negotiation rather than national prescription'.

Measures in the bill allowing care trusts to be established on a voluntary basis, or by order of the health secretary, cleared the committee last week, with little amendment.An expected government amendment made provisions for either local government or NHS partners to exit from care trust agreements.

Age Concern policy officer Pauline Thompson said the joint local authority-health service bodies could cause confusion and the charity was worried that it would be 'difficult to untangle' which services were free on the NHS and which were social care services with charges.