The deputy prime minister, Nick Clegg, has set himself on a collision course with the health secretary, Andrew Lansley, by signalling his determination to veto a key plank of the government's controversial NHS reforms.

Clegg has singled out the role of Monitor, the NHS regulator, as the area of the embattled NHS bill that needs the "most substantial changes".

He has said descriptions of the body as an economic regulator should be removed on the grounds that the NHS cannot be regulated as though it were just a utility "like electricity or telephones".

In the blueprint of his health and social care bill, Lansley proposed that Monitor – which currently scrutinises hospital finances – is also given the duty of promoting competition in the provision of health services.

However, in a stance which directly opposes that taken by Lansley, Clegg believes Monitor should instead promote and protect the interests of the patient and push NHS collaboration.

Simon Burns, a Conservative health minister, sought to play down the impact of Clegg's opposition to the idea of an NHS regulatory body, insisting it would not derail NHS reforms.

"No it doesn't at all," Burns told the BBC Radio 4 Today programme. "As you know, we have a pause at the moment ... we are listening, we have set up an independent future forum that is going and talking to and talking to people in the NHS, to the Royal Colleges, others who have an interest and involvement in the National Health Service seeking constructive ideas in which we can continue to improve and strengthen the bill."

Burns said that the idea was one of many put forward as part of the listening exercise designed to improve the bill.

He added: "The deputy prime minister had a meeting, I understand, with his members of parliament last night, discussed this, they have come up with some ideas, like a load of other people throughout the NHS, and all those ideas will be considered when listening process is over, and the decision will be taken that will be aimed at improving, strengthening the bill, and making sure that patient care is first class."

Evan Harris, a former Lib Dem MP and the vice chairman of the party's federal policy committee, said Burns was "wrong" to say Clegg's comments were simply a contribution to the listening exercise.

"We have made very clear that there will be no government majority for things not in the coalition agreement, like this mass marketisation of the health service, without Liberal Democrat MPs and peers," Harris told Today.

"They will not vote for Monitor to be an economic regulator, so this is a veto."

In a presentation by Clegg to the weekly meeting of his parliamentary party, leaked to the Guardian, a page-long policy document signed by him set out how he believes the regulator should be reconceived.

"Instead of having a duty to promote competition, Monitor's main duty should be explicitly to protect and promote the interests of patients," he wrote.

A new role for Monitor has long been a running sore in the health secretary's plans. Last week, Steve Field, the man appointed by David Cameron to oversee the "pause" in the health legislation, said he also thought the proposed new role for Monitor should be scrapped.

Instead, it should promote co-operation and collaboration and the integration of health services.

Addressing fellow Liberal Democrat MPs and peers at a meeting on Tuesday night, Clegg said he would "never let the profit motive get in the way of the essential purposes of the NHS".

The policy document said: "We cannot treat the NHS as if it were a utility, and the decision to establish Monitor as an 'economic regulator' was clearly a misjudgment, failing to recognise all the unique characteristics of a public health service, and opening us up to accusations that we are trying to subject the NHS to the full rigours of UK and EU competition law.

The Tory backbencher Peter Bone accused the Lib Dems of trying to exploit the issue for political reasons, having previously backed the reforms in cabinet and the House of Commons.

Bone told Sky news Clegg's position as deputy prime minister meant he should be supporting government policy. If a Conservative minister had opposed the NHS reforms as Clegg had done, "he would have been fired by now", Bone said.

"Every minister must support it. If you can't support the decision, you must resign from the government," he added.

"Having voted for it in parliament, the only thing that seems to have happened is that the Liberal Democrats lost very badly in the local elections, lost the AV referendum and this seems to be more about shoring up Nick Clegg's position as party leader rather than anything to do with improving the health bill."

The deputy prime minister should "row in" behind reforms which, Bone said, were in the interests of not only the country but also of the patient.

"It is right that we should listen and scrutinise the bill, but the idea that competition does not improve the health service is ridiculous," he said. "It drives up efficiency and makes NHS hospitals more effective.

"Getting better value for money in the health service, and people getting treated better and quicker must be right. You have a prime minister who loves the NHS who made his first priority the NHS.

"You have a health secretary with more experience than any other politician. Those are the people who should be listened to, not someone who is trying to do it for party political reasons, such as the deputy prime minister."

As Clegg seeks to establish a more distinct identity on issues like NHS reform after the Lib Dems' dismal poll results earlier this month, the former cabinet minister David Laws cautioned his Lib Dem colleagues not to put the coalition at risk by sniping at their Conservative partners.

Laws' comments – in his first interview since being barred from the Commons for seven days on Monday – will be seen as a warning to ministers such as Chris Huhne and Vince Cable, who have gone public with criticisms of Tory colleagues.

Laws, who was suspended after the parliamentary standards commissioner found he breached expenses rules by claiming the rent he paid his male partner of nine years, said: "Our continued effective delivery of policies depends not just on shouting and our public profile, but on a trusting relationship between the key people in the coalition.

"We could get our way over one or two key issues by storming off, voting against them, briefing against them, whatever. But when the next key issue is on the table and we need the co-operation of everybody in the coalition, will we get it? Maybe we won't."