Mental health may not be put on an equal footing in the NHS without compromising other services, a cross-party group of MPs has concluded.

The highly-respected Public Accounts Committee has said 'parity of esteem' may be difficult to achieve on the current budget, and that there was no plan to develop the workforce needed to tackle the issue.

One in four adults is diagnosed with a mental health illness at some point in their lives, but only around a quarter of people estimated to need mental health services have access to them.

The committee also found there was no consistent way to access mental health services for people leaving prison, inconsistent access to counselling in schools and said the NHS and Department for Work and Pensions were not getting people suffering from mental health illness back to work.

Meg Hillier, the chairman of the PAC, said: 'The Government has committed to making much-needed improvements to mental health services but we are concerned it does not yet have sound foundations to build on.'

Central Suffolk and North Ipswich MP Dr Dan Poulter, who works part-time in psychiatry, said the government was rightly committed to parity of esteem between mental health and physical health, but there was still a long way to go in ensuring adequate funding hit the ground where and when it is most needed.

He added: 'Considerable additional investment in frontline mental health services is needed in order to ensure that patients receive the highest quality of care, and to help the different parts of our health and care system, including housing providers, to work together more effectively in providing the integrated care that people with long term mental ill health deserve.'

It comes as former Liberal Democrat health minister Norman Lamb, who pushed for the same rights for physical and mental health patients, launched a new panel - the New Beveridge Group - to look at NHS funding.

He raised the prospect of a tax increase to ensure all NHS services are properly funded, potentially through a dedicated NHS and care tax.

Mr Lamb said: 'Most of us do not want a bargain basement NHS where people with mental ill health still suffer outrageous discrimination in terms of access to treatment.'