NHS bosses have admitted there is no 'definitive timeline' for when changes will be made to the region's failing mental health services.

Seven MPs from across Norfolk and Suffolk wrote to regulator NHS Improvement (NHSI) last month to demand the 'chaos and confusion must end' over Norfolk and Suffolk Foundation Trust (NSFT). And they insisted a plan of action should be published by February 20.

But Ian Dalton, NHSI chief executive, said although a 'package of support' had been provided to NSFT, he was 'unable to provide a definitive timeline' for any proposed changes.

NSFT was rated as inadequate for the third time in November. Mr Dalton said: 'I am encouraged that there has been some improvement at the trust over recent weeks, but there is work to be done to ensure that improvement is accelerated and sustained.'

The seven MPs, from across party lines, who originally signed the letter included Norman Lamb, Clive Lewis, Sir Henry Bellingham, Richard Bacon, George Freeman, Peter Aldous, and Dr Dan Poulter. Mr Lamb, Liberal Democrat MP for North Norfolk, said the reply 'still leaves [him] unclear about the future' of the trust.

MORE: Cross-party letter demands end to 'chaos and confusion' in Norfolk and Suffolk mental health

He said: 'NHSI seem to be very determined to prove they can turn around NSFT as an existing organisation without change. They refer to the fact they've put an improvement director in place but I believe she is also the improvement director for two other Norfolk trusts, and I find that an extraordinary position for NHSI to take.'

Mr Lamb said he had never heard from improvement director Philippa Slinger, and she last year refused to speak to this newspaper. But NHSI previously said an improvement director was just one part of a turnaround plan.

Mr Lamb added: 'I think they need to come clean about what the plan is. I think the Norfolk public deserve to be levelled with. They don't have to say now whether they are splitting the trust or keeping it together, but what are the steps that are being taken on making a decision on these things?'

An NHSI spokesman said: 'We continue to provide intensive support to the trust and are working with partners in the local healthcare system to ensure that sustainable improvements are made for patients.'