The prime minister has insisted Britain must keep its "options open" on membership of the single currency.

The comments came amid speculation that plans for an early referendum had been scrapped following the Swedish "no" vote on euro membership.

Speaking in the Commons Tony Blair said he would not close down debate on the single currency.

"We should do what is right for this country and keep our options open," he said.

But Iain Duncan Smith mocked the prime minister - demanding to know where the government's much vaunted "euro roadshow" had got to.

The government's roadshow "hasn't even got on the road", the Commons was told.

"The whereabouts of his own roadshow is a mystery even to his own government," said Duncan Smith.

"The Treasury says when asked 'there are so many roadshow events we can't begin to list them all'.

"But the Foreign Office said that 'the roadshow hasn't actually begun'.

"Meanwhile the minister for Europe said 'it's not a literal roadshow it's only a figure of speech'."

And he called on the prime minister to admit that there "won't be a referendum in this parliament".

"His dreams, his schemes his hopes to scrap the pound are utterly wrecked," said the opposition leader.

Blair dismissed the attack insisting that the right test to apply would be whether membership is in the "economic interests" of the country.

"I see absolutely no reason for this country to say it will foreclose its options and rule out membership of the single currency," he said.