In a sign of the times, the National Debt Clock in New York City has run out of digits to record the growing figure.

As a short-term fix, the digital dollar sign on the billboard-style clock near Times Square has been switched to a figure - the "1" in $10 trillion.

It is marking the federal government's current debt at about $10.2 trillion (£5.9 trillion).

The Durst Organisation says it plans to update the sign next year by adding two digits. That will make it capable of tracking debt up to a quadrillion dollars.

The late Manhattan real estate developer Seymour Durst put the sign up in 1989 to call attention to what was then a $2.7 trillion debt. In a press conference on the financial crisis on Wednesday, US Treasury Secretary Henry Paulson said: "We will use all the tools we've been given to maximum effectiveness, including strengthening the capitalisation of financial institutions of every size," he said.

Mr Paulson said "the turmoil will not end quickly and significant challenges remain ahead".

He added that "US and global financial markets continue to be severely strained".