The prime minister and the chancellor have begun meeting with Cabinet members today to discuss Britain's approach to the euro.

Tony Blair and Gordon Brown will quiz ministers on their response to the Treasury's technical documents on British entry into the single currency.

Having spent the weekend weighing through the 18 documents, amounting to 2500 pages of detailed economic analysis, the Cabinet will now get the opportunity to feed their opinions into the government assessment on the five economic tests for euro entry.

Downing Street refused to say which individual ministers were meeting Blair and Brown - insisting it would not provide "a running commentary" on events.

The chancellor will give a statement to the House of Commons on the outcome of the tests on June 9, after a series of special Cabinet meetings and this week's unusual trilateral discussions.

It is widely expected that the Cabinet will say "No" to recommending a referendum at this point.

But debate centres on whether to keep open the option of reassessing the tests within the lifetime of this parliament and campaigning for entry before the next general election.

Brown is thought to be sceptical about the chances of winning a national euro ballot before 2006, whereas Blair and a majority of Cabinet allies want to keep the idea alive.

The prevarication has led the Conservative leader to end his party's self-imposed silence on the issue and begin to voice his long standing objection to the single currency.

Iain Duncan Smith said that "no government can get round the idea that at some point you have to make choices".

The chancellor's five tests were a "sham", he claimed, "as there is no case for saying that any of these tests have been met".

Brown moved to quell speculation over his position over the weekend by pledging to fight for a euro Yes vote if his five key tests are met.

The chancellor told the BBC that both he and Blair are united in their determination to "make the right decision in the right way".

He said that he will work just as hard as the prime minister to achieve a Yes vote in a referendum if the five tests are met.

But the tests will remain "the centrepiece" of the Cabinet decision and his own announcement to the Commons on June 9, he said.

It will be the results of the tests, not political "dogma" which determine whether ministers recommend British entry, Brown claimed.

"The five tests effectively define the national economic interest for our country," said the chancellor.

"It is a guarantee that we can ensure jobs, investment and the future profitability of industry and the prosperity of the country.

"When I make the statement to parliament on June 9, the focus will be on these five economic tests that define the economic interests of the country."

Brown challenged media reports of his own euro scepticism by maintaining that he was committed in principle to entry into the single currency.

"Of course, if there were a referendum, then I would be urging, on the basis of the five-test assessment, a Yes vote," he said

The interview came as part of a concerted government effort to refute media reports that Blair and Brown are divided on euro membership.

There had been suggestions that while the prime minister wanted to keep open the option of a referendum later in this parliament, the chancellor had sought to rule it out until after the next election.

But both men have denied reports that they are at loggerheads over the euro.

In a joint statement issued on Friday, Blair and Brown said they were not "at odds" on membership of the single currency.

Blair insisted he was not determined to call a euro referendum "come what may".

Brown added that it was "simply not the case" that he was opposed to a euro vote in this parliament whatever the circumstances.

"Once a decision is taken, the prime minister and chancellor will be on exactly the same page, in total command of all the arguments and confident of winning support for the final agreed position," the statement said.