They will begin work together to promote closer links with Europe and will endorse a UK-wide campaign on the issue.

Single-currency umbrella group, Britain in Europe, is to formally launch its campaign on Thursday with a meeting involving Chancellor Gordon Brown, Prime Minister Tony Blair and former Tory cabinet ministers Kenneth Clarke and Michael Heseltine.

BBC Scotland's Political Editor Brian Taylor reports

The Scottish party leaders - including Liberal Democrat Jim Wallace - will launch their own campaign a week after the London event.

It is widely expected that the Tories in Scotland will stage a counter campaign.

Alex Salmond said on Sunday: "I am not worried about Labour's internal politics. And I think the Tories anti-European stance south of the border should be put to one side.

Common ground

"I think there will be more common ground in Scotland than elsewhere in the UK."

But Mr Salmond was critical of what he called Labour's "anaemic view" of the single currency.

"I am rather disappointed with the lack of strength of commitment to the Euro. Labour seem to have a rather anaemic commitment. You can only win the argument if you are prepared to argue for it," said Mr Salmond.

However, Labour MSP Hugh Henry said the UK chancellor and prime minister were right to establish firm conditions before joining the single currency.

"We have to make the right choice at the right time for this country," he said.

Despite rows over points of detail, Labour is delighted with the SNP's involvement in the UK-wide campaign.

Congratulations

Mr Henry said: "I think Alex Salmond has to be congratulated on the fact that he is willing to work with parties at a UK level. He may have questions to answer with his own party's members, but outside that this is a good move."

The Tories in Scotland have reiterated their mixed view on the subject of Europe.

Brian Monteith, Conservative MSP for mid-Scotland, said: "We are clear that we want to be in Europe but we do not want to be run by Europe. What is important here is that we are against the European currency."

And he was quick to criticise the SNP's involvement with its political rivals.