Hundreds of recent NHS board appointments are to be investigated after the Department of Health admitted that an error during a trawl for new members may have led to a disproportionate number of Labour councillors getting jobs.

The independent commissioner for public appointments, Sir Len Peach, agreed to the audit after complaints by shadow health secretary John Maples that the government 'manipulated' the process for political reasons.

However, Sir Len made it clear that DoH officials, rather than the government, were responsible for the error, and he dismissed Mr Maples' main allegation that health secretary Frank Dobson had a secret agenda to pack boards with Labour councillors.

A letter from Sir Len to Mr Maples explains that a draft letter prepared by the DoH for regional chairs to send to local authorities in June was addressed to council leaders, and did not make it clear that minority parties were to be consulted.

Sir Len quotes from a letter to him from DoH permanent secretary Chris Kelly, which states: 'This was clearly an error as we quickly recognised... in retrospect it would have been more appropriate to have addressed the letter... to chief executives.'

Mr Maples said his own survey of 76 councils revealed that 54 Conservative group leaders had not been consulted over their council's nominations to NHS boards.

Sir Len said he was satisfied that this was a 'communications failure' by DoH officials which was rectified in subsequent trawls. He added that he has asked auditors to test whether the error had affected the quality of appointments.

'I will ensure that they pay particular attention to the processes by which local authority members were nominated and the competition to which they were exposed, and the evidence which suggested they were appointed on merit.'

Mr Maples also claimed that a leaked letter by North Thames regional chair Ian Mills to a Conservative councillor inferred that Mr Dobson was secretly seeking 'a significant increase in local authority representation'.

Sir Len said that Labour had always made it clear that it would seek nominations from local authorities which would be judged on merit in competition. 'The secretary of state will surely argue that he has tapped a previously neglected source of candidates,' he added.

Other allegations include:

Anne Galbraith, the former Newcastle Royal Victoria Infirmary trust chair, was informed that her contract would not be renewed when she was telephoned by her successor;

Patricia Perkins, a non-executive director at Kettering General Hospital trust, was told by her trust she would be reappointed, but was not. It is claimed she has never been formally informed of the decision.

Sir Len said that by 12 January, 80 per cent of all trust appointments had been completed.