Downing Street is planning a 2004 single currency referendum, it has been claimed.

Former minister Peter Mandelson has hinted that a referendum is more likely to come next year.

Insiders say that the decision to delay is part of a longer-term campaign to take the UK into the eurozone.

"A decision to go for a referendum in 2003 - or 2004, as the case may be - would not lead to actual membership until at least two years later," argued Mandelson.

Writing in the Times, the former cabinet minister urged the chancellor to be more upbeat about the benefits of the single currency.

He argues that convergence between sterling and the euro would follow announcement of the UK's intention to join the eurozone.

The Hartlepool MP calls on Gordon Brown to base his five tests on the economic picture two years after a referendum on the single currency - a move that would be likely to follow a global economic recovery.A delay is also backed by Tony Blair, according to reports in the Independent newspaper.

According to an unnamed minister, Tony Blair wants to "play it long" by prolonging a planned four month campaign to between six months and a year.

"The process is serious and must be seen to have credibility. If we move straight from the assessment into a campaign, it would be too crude and look like a fix," the source said.

A new poll has also strengthened the case for the chancellor's caution.

A MORI poll of Britain's bosses reveals that 50 per cent are opposed to participation in the single currency.

Boardroom backing has fallen from a 70 per cent majority for the euro in 1997 to 42 per cent, finds the survey.