Downing Street has claimed public opinion on the euro will play no part in deciding whether a referendum will happen.

Number 10 reaffirmed its commitment to the euro on Monday despite Sweden's decision to reject the single currency.

"There has never been a sixth test," the official spokesman told ePolitix.com "The government will make the case to the British public should the economic conditions be right."

Despite the "no" vote in Sweden, Number 10 swept aside any claims that Britain would delay a referendum.

"It doesn't affect our own policy on the single currency. We are clear that the government will only recommend joining if the economic case is clear and unambiguous," said the spokesman.

Whilst there was a commitment that the issue would be "revisited at the time of the budget", there was no commitment to either a poll ahead of the next general election or the prime minister's "euro roadshow".

British opponents of the European single currency welcomed the result of Sweden's referendum.

Of the 97 per cent of Swedes that voted on Sunday, 56.3 per cent voted against adopting the euro, with 41.7 per cent in favour.

It follows fevered speculation that reaction to the murder of foreign minister Anna Lindh would boost the "yes" campaign.

Polls in the days leading up to the election suggested that the result was too close to call.

"The bulk of the media and political parties in Sweden were arguing for the euro. Despite that, Swedes have chosen not to give up their currency and not to adopt a one-size-fits-all interest rate," said shadow foreign secretary Michael Ancram.

"It is clear that being out of the euro will not leave Britain isolated in Europe.

"Blair's euro campaign is now severely damaged."

Former Europe minister Keith Vaz conceded that the Swedish result was a "bitter blow" to pro-euro campaigners in Britain.

"The main lesson to learn for the prime minister and the government is that they have to put into deeds the good words they have said about being pro-euro," he said.

"This means that the campaign for the euro must start now.

"After Gordon Brown gave us the results of the assessment of the five economic tests the prime minister promised that the cabinet would lead the euro campaign in Britain.

"This simply is not happening. Unless we begin the campaign immediately, the euro referendum campaign in Britain will be over before it's begun."

This assessment was rejected by leader of the Commons Peter Hain.

"Just as the Swedes are making their own decision about the euro today, so we will make our own decision in Britain's interests in the right economic circumstances," he told Sky News.

But speaking to the BBC Radio 4 Today programme on Monday, shadow chancellor Michael Howard argued that the single currency was a "dead duck".

"The issues are whether people think that the important issues affecting their daily lives, affecting their livelihoods, should be decided by their democratically-elected governments in their own country or should be imposed on them by the European Union," he said.

"The Swedes have given a clear answer to that question.

"I think the people of our country will give a clear answer to that question, if they are ever asked the question in a referendum on the euro."