A powerful watchdog has warned that the NHS has "much to do" before it can deal effectively with a major incident such as that seen on September 11 last year.

The National Audit Office says there are serious gaps in the way the NHS and ambulance service would respond to a crisis.

"This would be worrying were we speaking simply of the types of disaster we have experienced in the past, such as plane and train crashes," said Edward Leigh, chairman of the public accounts committee.

"It becomes even more disturbing when we learn that, in a number of crucial aspects, the NHS could be better prepared for dealing with post September 11 threats including the deliberate release of hazardous substances."

In a report published on Friday, the NAO said that acute and ambulance trusts have identified major gaps in their ability to respond to chemical, biological, radiological and nuclear incidents.

"I am concerned to read that only one in 10 trusts consider themselves well-prepared for a chemical incident and even fewer think they are well prepared for a biological incident," said Leigh.

"No fewer than a half of acute trusts and one third of ambulance trusts think that key staff have not been sufficiently trained in the use of protective and other equipment."

Large numbers of trusts also regard their protective equipment and decontamination facilities as poor, the report found.

"It seems that weaknesses prevail at the national level as well as locally in trusts," added Leigh.

Whilst he conceded that the report points to "a moving picture", Leigh warned that the NHS "needs urgently to build on the improvements they have made in emergency planning since September 11".

"New threats now face us and the public will want to be assured that everything possible has been done to prepare for them," he added.