IMF managing director Horst Koehler told the United Nations: "The global economic outlook is improving. Prospects for a recovery are firming in the advanced economies, led by developments in the United States."

The annual rate of growth accelerated from 3.3 per cent in the second quarter to 7.2 per cent in the third quarter, the strongest such figure for 19 years, US official data showed on Thursday.

But economists are cautious about the real impact this is likly to have in Europe, and when.

Some expect the US economy to slow down from the middle of next year when the effect of tax cuts by President George W. Bush fades.

The EU Commission published data on Friday showing that its business climate indicator had risen by almost 0.25 points from September to October to minus 0.18, the highest value since May 2001.

And official data in Britain a week ago showed third-quarter growth steady at 1.9 per cent on a 12-month basis, from 2.0 per cent in the second quarter.

In London, an economist at Investec Securities, Philip Shaw, said: "I'm not sure that yesterday's GDP figures from the States will have a lasting impact on the economic climate in the UK.

"Despite the fact that the numbers were very very robust they were buoyed by a temporary spike in consumer growth through tax cuts and the tail end of the mortgage refinancing boom.

"So the likelihood is that US growth will decelerate in the fourth quarter and perhaps be somewhere around sustainable levels in the first half of next year.

"Where this leaves the eurozone is not exactly clear. Despite the fact that we've seen improvements in business sentiment across much of the euro area economies, there's very little evidence of a punchy upturn on the ground from official data.