Our main objective is to see that we have more price transparency

EU spokesman Gerassimos Thomas

Experts are concerned not only that consumers will be swindled, but also that price rises could boost inflation.

The Commission issued the warning as it unveiled the results of a Eurobarometer poll showing that two-thirds of European citizens fear cheating on prices once the euro comes into circulation.

The figure of 66% was up 5% from May.

Confidence

"Consumers have to be vigilant," said EU spokesman Gerassimos Thomas.

"Our main objective is to see that we have more price transparency... We very much insist on that."

Euro survey

90% say the euro will make travelling easier 73% know changeover date 66% fear price rises 56% think the euro will promote economic growth 45% expect more advantages than drawbacks 43% expect more drawbacks than advantages 30% have tried to remember prices in euros

Though he said there was so far no evidence of widescale price rises, the Commission has suggested governments monitor prices more often than once a month, and even once a week around the transition period.

Not all governments have yet responded positively, so European Monetary Affairs Commissioner Pedro Solbes plans to raise the issue at this month's meeting of eurozone finance ministers.

Allaying concern about euro-linked price rises would help boost confidence in the new currency.

A Eurobarometer survey released in July showed that support for the euro had increased by 4% between autumn and spring to 59% across the EU.

Are euro informed?

Overall: 53% France: 64% Portugal: 37% Greece: 33%

However, the latest survey shows that only 45% in the 12 eurozone countries expected the euro to generate more advantages than drawbacks on a personal level, compared to 43% who thought the opposite.

In all countries except Germany the optimists outnumber the pessimists - by 5% in Finland and Austria, rising to 47% in Ireland.

In Germany however the balance is -29%.

Of those polled, 53% overall felt they were "well informed" on the euro.

France scored best in this respect, with 64%, while Portugal and Greece scored worst, with 37% and 33% respectively.

French checks

Some 73% of those questioned knew when the changeover was, but roughly one in five did not know that the euro would be accepted in other eurozone countries.

Earlier, the French Government announced a series of measures aimed at curbing price rises in connection with the changeover to the euro in four months' time.

The country's Finance Minister, Laurent Fabius, said the government would use 200 agents to carry out fortnightly checks on the prices of 20,000 products.

Mr Fabius said the government was determined not to allow the changeover to be used as what he called a "false excuse" for price rises.

A study by the ministry found that prices were already spiralling in some sectors - among them bakeries and hair salons - although they had remained "reasonable" overall.