Although the single currency was practically unchanged against the dollar on the week, it hit a fresh seven-month low of $1.2495 on Thursday after the latest French polls showed that 55 per cent were likely to vote No. to the constitution

"A rejection by France will make it difficult to deal with new budget discussions, the Lisbon agenda of economic reform and foreign policy issues. This could further damp confidence in the euro at a time when weakening growth, especially relative to the US, has already put significant pressure on the single currency," said Mitul Kotecha, a Calyon strategist.

With the likelihood of a No vote already already 65 per cent priced in, according to spread betting agency IG Index, few were expecting major fireworks at currency trading desks next week. But against the backdrop of slowing eurozone growth and a seemingly immovable European Central Bank, "euro weakness has further to run this year", added Mr Kotecha.

The ECB came under growing pressure this week to loosen its grip on monetary policy and allow for the increasing weight of evidence in favour of cutting rates to help boost growth. On Tuesday, Jean-Philippe Cotis, chief economist at the Organisation for Economic Co-operation and Development, suggested the ECB should lower rates.

The following day Hans-Werner Sinn, head of the Ifo institute, echoed this suggestion after business confidence in Germany fell to its lowest level in nearly two years. Mr Sinn said the central bank's inflation target of 2 per cent was too low.

If the bank's governing council votes to keep interest rates on hold when it meets on next Thursday, the main refinancing rate will have stood at 2 per cent for two years.

"The ECB will need some time to get itself out of the hole it has dug for itself by saying repeatedly that rate cuts are not an option," said Mark Austin, strategist at HSBC.

By midday in New York on Friday, the euro had fallen stood at $1.2573 against the dollar, up 0.2 per cent on the week.

The euro gained against sterling after Wednesday data showed the UK economy grew at its weakest rate in nearly two years. It stood at £0.6880, up 0.3 per cent on the week. Sterling was down 0.2 per cent against the dollar over the week at $1.8235.