The world grouping OECD said yesterday the global economy had come out of "freefall", offering hope of recovery late this year, but investors focused on risks to the US credit rating from rising government debt.

Japan's Central Bank governor also said new data now banished notions of the world's second-biggest economy "falling off a cliff".

The US dollar dropped to a 2009 low as fears grew that the United States could be at risk of being stripped of its precious triple-A rating, which would have wide implications for global investment already throttled by the crisis.

Ratings agency Standard & Poor's stirred concern on Thursday by suggesting Britain could face such a downgrade.

"Is this a warning shot or is it the start of a trend? This is very dangerous territory," said Axel Merk, president and chief investment officer at Merk Mutual Funds.

US stocks were slightly higher yesterday, in part on comments by Moody's that the ratings agency is comfortable with the US triple-A rating "but it is not guaranteed forever".

The United States, where last year's housing market collapse set off the crisis now hitting trade and industry worldwide, has been running up government debt as it uses billions of dollars to bolster the financial system and stimulate the world's largest economy.

The head of the Organisation for Economic Cooperation and Development (OECD), Angel Gurria, said ratings agencies must "recover their prestige and credibility" after being widely criticised for failing to predict the crisis.

"It seems absolutely inexplicable that they want to cut the rating of England and that there is talk they are going to cut the rating of the United States," he said.