Gordon Brown has been urged to adopt a clear "roadmap" for taking Britain into the single currency.

The call came from leading politicians and business figures keen to ensure that the government steps up the momentum towards membership of the single currency.

Senior figures including former Conservative foreign secretary Lord Howe and GMB general secretary John Edmonds urged support for a 10-point plan on joining the single currency.

With the Cabinet set to take the final decision no the five tests on Thursday, pro-Europeans warned that without a clear commitment Britain risked losing influence with European allies needed to win debates about the proposed EU constitution and on economic reform issues.

The roadmap calls for any obstacle to euro membership to be accompanied by a plan for overcoming it.

There should also be a full Treasury assessment of the costs of staying out, said the campaigners in a document published by the Foreign Policy Centre.

"The government have got to stop acting as if euro membership is out of their control. Wrapping a deferred referendum in pro-European rhetoric will fool no one," said Mark Leonard, director of the Foreign Policy Centre.

"Unless the Cabinet pursues a clear strategy for joining, Britain will be in the same position after the next election and the polls will look just as bad for the Yes camp"

Lord Howe, former chancellor and foreign secretary, said: "We've spent enough time trying to read the crystal ball. The most important thing is a clear affirmation that it is unambiguously in Britain's interest to join the single currency.

"The prime minister and his Cabinet must now set about making the positive case. It's high time for the government to set out a road map as clear as this."

And GMB chief John Edmonds said that government supporters would not understand further delay.

The 10 point euro roadmap plan

• If any deferral of the referendum is to be credible, every obstacle to entry outlined by the chancellor must be accompanied by a plan for overcoming it as well as a full Treasury assessment published of the costs of staying out.

• The government should establish a euro strategy group chaired by the prime minister and including the deputy prime minister, the chancellor, the foreign secretary, the secretary of state for trade and industry, the secretary of state for work and pensions, the Leader of the House and the lord chancellor - to consider the myriad of practical issues that need to be taken into account.

• The prime minister must instruct Cabinet ministers to make the case for the euro and outline the political as well as the economic costs of exclusion. The decline in Britain's percentage of EU inward investment - from 28.3 per cent in 1998 to 5.1 per cent in 2002 - must become a government mantra.

• The government should bring forward legislation paving the way for a referendum on the euro, including details of timing, the wording of the question, and the polling arrangements.

• The government should introduce tax-breaks for small and medium size businesses to help alleviate the costs (such as IT upgrading) of changing currencies.

• The government should publicly announce that it supports the European Council's new proposals to introduce flexibility into the stability and growth pact so it can accommodate cyclical downturns in the business cycle. Reforms are in the offing that require the budget to be 'close to balance or in surplus' over the whole economic cycle. Countries with low debt ratios and sustainable public finances should be allowed to run modest deficits to finance investment in public services.

• The government should announce that it supports the European Central Bank's proposals to abandon the special status for money supply growth and adopt a specific inflation target similar to that of the Bank of England's.

• The government should introduce measures that encourage a wider spread of fixed rate borrowing - and reduce the British economy's sensitivity to free-floating interest rates.

• The government should welcome the benefits to British industry brought about by the recent strengthening of the euro against sterling. It should commit itself to negotiating a sustainable rate at the time of joining.

• The government should publish a consumer code of practice and set up price monitoring mechanisms. This will help to prevent consumers being exploited during the changeover to the new currency.