A cabinet member from Prime Minister David Cameron's junior coalition allies dismissed his decision to veto an EU treaty change as a political move that bought a popularity boost at home but left Europe's problems unsolved.

Cameron's veto of an EU deal to help address the debt crisis in the euro zone won him a hero's welcome at home with his broadly eurosceptic Conservative Party but opened a rift with his junior coalition partners, the Liberal Democrats.

It was largely political, Lib Dem Business Secretary Vince Cable said of Cameron's stance.

Certainly the prime minister has got a short term boost from it. But it doesn't actually deal with the big long term problems in Europe, Cable told BBC TV on Sunday.

Cameron has not only seen his personal standing in his party rise, but his actions have also led to the Conservatives' popularity soaring, with one poll on Sunday putting them six points ahead of the Labour opposition.

The pro-European Liberal Democrats have seen their own popularity tumble since they joined Cameron's government in May 2010, leading to awkward questions for party leader Nick Clegg, the deputy prime minister.

Cameron's move - which will force countries using the euro currency to adopt new fiscal rules in a treaty among themselves rather than a treaty change for the entire EU - left Britain isolated among the 27 EU members.

Clegg called Cameron's veto bad for Britain, and Lib Dem lawmakers abstained from a parliamentary vote praising it.

Clegg is under pressure to demonstrate Lib Dem differences with the Conservatives, without bringing down the coalition which he says will last until the next election in 2015.

On Sunday, Clegg took a swipe at Conservative eurosceptics he said were predicting the demise of the euro with a sense of glee, including some who hoped the crisis would pave the way for a referendum on pulling Britain out of the EU altogether.

Our vital economic national interest is based on us being and remaining at the heart of Europe, Clegg told Sky News. We are at our best as a country when we engage, when we're open, when we lead, not when we kind of retreat to the sidelines.

Britain needed to move past a war of words with European countries, particularly France, that has been sparked by Cameron's veto, Clegg said.

You're getting this kind of pressure cooker environment in which some words are said which aren't wise, Clegg said. But I think everybody knows that we need to move forward and work together where we can because that's the only way that we are going to get out of this mess.

Clegg is expected to use a speech on Monday to criticise Conservative plans to introduce a tax break for married couples. Newspapers briefed on the speech said it would also include other digs at Conservative policies in a bid to reassure Lib Dems who see Clegg as too close to Cameron.

Clegg told Sky the marriage tax break showed the parties had a philosophical difference, but would not make much of a difference in whether people decided to marry.