City bosses are to be asked to review preparations for a September 11-style terror attack.

In a green paper published on Tuesday, ministers detail how the government and financial institutions would cope with a possible terrorist outrage.

The consultation, which ends on April 25, covers a range of catastrophic events that could cause "major operational disruption" - such as a terrorist attack, adverse weather conditions or a computer virus.

In the event of a serious incident, the City will still have to meet agreements to pay for deals made on shares, bonds and derivatives markets, ministers warn.

Treasury officials want to know if new powers should be created to allow authorities to suspend key financial system obligations such as exchanges and clearing houses.

"The September 11 attacks on the United States caused terrible loss of life and physical damage," said Treasury financial secretary, Ruth Kelly.

"They also showed the problems that physical disruption on such a scale brings for the financial system - as exemplified by the four-day closure of the New York Stock Exchange."

She added that financial services play a vital role in the UK economy.

"This makes it particularly important to be sure that we have good arrangements in place to maintain the financial system's resilience during major operational disruption."