The chancellor moved to reassure Labour MPs yesterday that neither he or the government were forever against the currency.

Speaking during Treasury questions, Gordon Brown insisted that the decision should be based on economic realities and not dogma.

"We are looking at investment, we are looking at employment, we are looking at financial services, we are looking at sustainable convergence, we are looking at issues of flexibility.

"It would be wrong for this country to rule out the single currency, as the Conservatives want to do, as a matter of dogma," he said.

Pro-euro campaigners tell the FT today that Tony Blair "lacks bottle" over the euro issue.

Meanwhile, 300 international economists have urged the chancellor to declare that Britain has passed the five economic tests and prepare for euro entry.

The economists include Paul Volcker, the former head of the US central bank, Stanley Fischer, a former IMF managing director, the Nobel laureate Professor Robert Mundell and Lord Kingsdown.