As the deadline for Gordon Brown's euro announcement approaches, splits are appearing within both the government and the business community.

Following a weekend in which Cabinet divisions on the issue were exposed, Monday saw senior business figures disagreeing over whether the option to join the single currency later in this parliament should be kept open.

Meanwhile, Number 10 has confirmed that the chancellor and Tony Blair continue to have "intensive discussions" on the issue.

On Sunday the chancellor was warned that the Cabinet, not the Treasury, will decide Britain's policy towards the euro.

John Reid, leader of the Commons and a close ally of the prime minister, told ITV's Jonathan Dimbleby programme that the decision was "not whether we will join the euro, but when".

"When he [Brown] and the Treasury give an estimate on these things of course it is extremely important. But ultimately these decisions are taken by the Cabinet under the leadership of the first lord of the treasury who is the prime minister...the Cabinet will discuss these matters collectively," he said.

Amid mounting concern among pro-euro campaigners that Brown will seek to rule out a euro referendum before the next general election, the chancellor also took to the airwaves to offer reassurance.

He told GMTV's Sunday Programme that it would be wrong to "rule out the euro on grounds of dogma, something that is unacceptable to me".

But he also stressed the need to continue the process of economic reform within the European Union.

Downing Street said the Cabinet would be involved in discussions before the final decision is taken.

"In terms of precisely when that will be, I can't tell you. I don't think it is settled yet," the official spokesman said.

Many experts predict that lack of reform will be a key reason for ruling out immediate membership of the euro when Brown makes his announcement, which is due before the first week of June.

Meanwhile, business leaders have joined ministers in sending mixed signals on the euro.

The British Chamber of Commerce warned that the forthcoming euro announcement should not leave the door open to a further assessment before the next general election.

Director general David Frost said it was "absolutely vital to ensure that the euro verdict does not add to the uncertainties facing UK business".

But pro-euro campaigners have published a letter signed by 25 business leaders which warns that any decision to rule out entry for the rest of this parliament will damage Britain's economy.

Chris Gent, chief executive of Vodafone, Peter Sutherland of BP and former Treasury minister Lord Simon are among the signatories.

The latest comments follow a warning by the Britain in Europe campaign group that it could collapse if the government fails to set a deadline for joining the currency.