The opposition said the decision had more to do with splits on the wisdom of joining the euro than it did about the economics underpinning membership.

"This whole exercise has been a deceit," said shadow chancellor Michael Howard.

"The only reason we are not having a referendum now is that they know they can't win it."

Howard turned to focus on the splits between Tony Blair and Gordon Brown: "There they sit, united in rivalry, each determined to frustrate the other, to scheme against the other, to do the other down.

"So there is no clarity in policy, there is no consistency of purpose. Blair goes one way, Brown goes the other way and bang goes the third way - lost in compromise and confusion."

Liberal Democrat Treasury spokesman Matthew Taylor said that the government had in effect said "no" to the euro.

"The time for indecision is over. Warm words are not enough. It's time for action. On that, the jury is out," he said.

"Two assessments, three national changeover plans, 18 studies, 2000 pages, endless spin, but still indecision. He said it would be prepare and decide. It was actually, for the prime minister, wait and see."