Tony Blair has said he is ready to confront the "big issue" of the single currency.

The prime minister said "it would be a shame" if Britain was left behind in the EU - adding that he would trust the people to make "a big constitutional decision".

The remarks have renewed speculation that the prime minister still intends to hold a euro referendum during this parliament.

His comments come as European Commission figures to be released today will show that inward investment in the UK has plummeted since the launch of the euro.

The move will be seen as fresh evidence that the British economy will suffer unless the country joins the euro.

Meanwhile, every member of the cabinet will today receive a letter signed by 10 former trade ministers who warn that Britain's success as a trading nation will be at risk if the government rules out membership of the single currency.

The signatories - who include Peter Mandelson and Michael Heseltine - say that Britain would now be better off by £12 billion if the country had joined the euro at its launch.