Tony Blair has claimed there is an "emerging consensus" between senior ministers on the issue of the euro.

Addressing the media amid reports of deep splits over the single currency, the prime minister said the Cabinet is taking part in "serious and detailed" discussions about British membership.

"The chancellor and I have spent much of this week in discussion with our Cabinet colleagues and we have just had the first of two full Cabinet discussions in advance of the chancellor's announcement next month," he said.

"I think there is an emerging consensus from those discussions which have been serious and detailed and reflect out determination to make the right decision in the right way."

Blair insisted that all members of the Cabinet were now full square behind the principle of euro membership.

"Each member of the Cabinet, and today the Cabinet as a whole, has it made clear their support for the principle of joining the single currency with its potential benefits to Britain, British jobs and the standard of living of the British people," he told the media at a Number 10 briefing.

"And in addition each has made it clear that that decision must be based on a rigorous assessment of our long term economic interest.

"It's the biggest decision that we face as a government and we have to get it right and I am confident that based on the discussions that we have had so far that we will."

The prime minister also promised to take the debate out into the country in a bid to overcome public opposition to the euro.

"This is a big debate. I relish that and I relish being part of it," he said. "I think it is possible for opinion polls to change."

Ahead of the public debate Blair counselled the British people against backing a "retreat to the margins of Europe".

It is widely expected that senior ministers will next week be told that the chancellor has decided that his five tests have not been met.

But pro-euro ministers, led by Peter Hain, are pressing for the door to be left open for a second assessment on the convergence between Britain and the eurozone.

At a 50-minute Cabinet meeting Gordon Brown is thought to have come under pressure over his increasingly euro-sceptic stance.

Cabinet ministers have met individually and in groups with Brown and Blair during the course of this week.

The prime minister and the chancellor have dismissed claims that they are at odds over the single currency.

But behind the scenes briefings have increased speculation that the relationship between the government's two most senior members has reached a new low.

Downing Street was on Wednesday forced to slap down Peter Mandelson after he claimed that a "politically obsessed" Brown had blocked Blair's calls for an early referendum.

Mandelson was speaking purely "as a backbencher on his own behalf", said Downing Street.

"The important thing is that the prime minister and the chancellor are meeting their colleagues, discussing what is one of the most serious issues that they are facing," said a spokesman.

"Only those involved in these discussion know the reality and know the substance. There will be all sorts of people saying other things and contributing to the public debate."

Clare Short also went public - insisting that the government had already decided to rule out membership for the time being.

"I understood that the prime minister and the chancellor had agreed that not yet, but keep open the possibility, depending on economic developments," she said.

Despite calls for calm, Labour feuds over the euro continued to spill out into the open. Senior Labour MP Clive Soley has warned Labour backbenchers against "vindictive briefings and personal feuds".