Senior ministers are said to be calling for a full cabinet debate on the single currency before Gordon Brown announces the results of his five tests.

Euro enthusiasts are said to be unhappy at the secretive way the chancellor has arrived at his conclusions.

The prime minister is also said to be moving to loosen Brown's grip on decisions concerning euro membership.

Tony Blair is also being told to develop new tests in order that the possibility of euro membership is not killed off by an initially negative assessment.