Ministers have promised further changes could be made to the government’s controversial health reforms as the plans were branded a “huge strategic mistake” by a senior Liberal Democrat.

Health minister Paul Burstow insisted the government “haven’t stopped listening” and would make further amendments to the legislation if necessary.

But John Pugh, co-chair of the Lib Dems’ backbench health committee, told the party’s conference in Birmingham that the proposals were a “huge strategic mistake” that would damage both parts of the coalition Government.

The Health and Social Care Bill progressed slowly through the Commons and was widely changed following concerns from Lib Dems, NHS professionals and patient groups, and the coalition government implemented a “pause” in the legislation while a listening exercise was carried out to recommend changes to the plans.

Mr Burstow insisted the legislation, which faces further difficulties in the Lords, had been improved since the Lib Dem spring conference passed a strongly worded motion opposing the shake-up.

The Lib Dem minister said: “The commitment I make to this conference is we haven’t stopped listening, we are keen to carry on listening, we are keen to make changes if they are needed to this bill to put beyond doubt that we as a party are committed to a comprehensive health service, free at the point of use, funded by general taxation and based on people’s need and nothing else.”

Mr Pugh said the bill had been “substantially improved” but added: “This is a huge strategic mistake for the government, not just the Liberal Democrats but also the Conservatives as well.

“There are two principle reasons for that: one, the scale of the reorganisation at times of severe financial constraint and secondly, the risks of reorganisation, some of which were actually bequeathed to us by the previous Labour government.

“But the situation is rather similar to that sickening feeling you have when you are on the motorway and you realise you have taken the wrong turning and you realise it will be some time before you get on the right track again.”

Lib Dem grandee Baroness Williams of Crosby, set to be at the forefront of the battles the bill faces in the Lords, said it must be made explicitly clear in the legislation that health secretary Andrew Lansley had a responsibility to provide a comprehensive health service.