Top economists believe the government's aim of reaching a "clear and unambiguous" assessment of the benefits of euro entry is impossible, according to a press report.

Eight leading economists polled by the Financial Times newspaper said there was no objective method of gauging whether adopting the euro would benefit the British economy.

"There is no purely scientific way of concluding that Britain's entry...would or would not unambiguously benefit Britain, the other euro countries, or the world as a whole," Robert Mundell, professor of economics at Columbia University, told the FT.

The FT poll reinforces the view that a government recommendation to join the euro would be motivated in part by political considerations.

The government is due to decide whether to recommend adopting the euro on the basis of five tests designed to assess whether the UK economy would be better or worse off within the single currency area.

The Chancellor of the Exchequer, Gordon Brown, has said the government will come down in favour of euro entry only if these tests are met "clearly and unambiguously."

In the balance

The government's verdict is expected within six months, although the final decision rests with the electorate.

If the UK government decides to back euro entry, it is expected to call a referendum on the issue before the next general election.

While recent surveys suggest that a majority of the British electorate is against adopting the euro, some sections of the business community, including most exporters, are in favour.

The pound's strength against the euro in recent years has made British goods more expensive, and therefore less competitive, within the single currency area.

Euro supporters also argue that adopting the currency would give Britain more political clout within the European Union.

Constraints

However, opponents say Britain's economy would perform less well under the European Central Bank's 'one size fits all' interest rate policy.

Some euro critics also argue that European monetary union should be seen as a precursor for even closer economic integration, warning that the UK may eventually face pressure to surrender control over tax policy if it adopts the euro.

The economists polled by the FT included three Nobel prize winners.

The three Nobel laureates were Gary Becker of the University of Chicago; George Akerlof of the University of California; and Robert Mundell of Columbia University, New York.

The panel included Alan Budd, a former member of the Bank of England's interest rate-setting committee.

The other members were David Hendry of Nuffield College, Oxford; Martin Weale, director of the Institute of Social and Economic Research; Wynne Godley of Kings' College, Cambridge; and John Muellbauer of Nuffield College, Oxford.