Public health experts say the system for alerting hospitals and GPs about health risks has worked.

But an intensive care consultant, one of those who should have been informed, told the BBC the only information he had received had come via the media.

If there was to be a major health risk ... it could be several days, maybe a week or two before key practitioners actually found the details   Intensive care consultant

He said: "Since the anthrax episode in the US, the Public Health Laboratory Service (PHLS) introduced an email alert system to key doctors up and down the country in the various trusts."

But, speaking on the night the news of the ricin find was announced, he said he had not received any information about the poison.

"Clearly there are implications that the communication system isn't efficient.

"And if there was to be a major health risk, not just terrorist related, but infection risk, it could be several days, maybe a week or two before key practitioners actually found the details."

Delay

Dr Sue Atkinson, director of public health for London said an email alert had gone out, and the system had worked as it should.

She said the information had been sent to hospitals and primary care trusts, and to the telephone helpline NHS Direct.

"We checked last night, and most of those had gone."

People must go about their daily lives and continue to function in a normal way   Dr Sue Atkinson, Public health director for London

She said there could have been a delay if the information had not been circulated within organisations.

"We have also had that information on the PHLS website and on the Department of Health website."

NHS Direct has received 47 calls from people concerned about ricin poisoning since the alert was issued on Tuesday, according to the Department of Health.

On a normal Tuesday, it would expect to receive an average of 15,000 calls.

The initial signs of ricin exposure are fever, a fast pulse and a feeling of weakness - flu-like symptoms.

Dr Atkinson said: "If you've got flu-like symptoms, you've got flu.

"But if people get sicker, they should go back and get treated."

She said people should not panic.

"The important thing is for people to be alert to these things. But we don't want people to be alarmed.

"People must go about their daily lives and continue to function in a normal way."

Paper suits

Victims of ricin exposure should be isolated and all their clothes removed and disposed of.

Their possessions should be placed in sealed bags to prevent contamination.

The victims should then be given paper suits.

Skin decontamination should then be carried out using a dilute detergent.

If the eyes have been exposed, they should be washed thoroughly with running water or saline for 15 minutes.

Doctors can only treat the symptoms of ricin poisoning. There is no antidote.

However, exposure is not always fatal, and people have recovered from receiving moderate doses.

The primary care group which covers the area of north London where the ricin was found has not heard reports from GPs of patients coming to see them concerned about the poison.

Dr Annie McGuiness, a consultant at London's University College Hospital, told the BBC it had plans in place for how it would deal with a ricin attack.

"If we had a lot of patients who were very ill, say with ricin poisoning, we have plans within the hospital to vacate beds, stop emergency admissions and to bring in extra personnel resources."

Poster campaign

Since the September 11 attacks, the NHS has stepped up its emergency planning for how it would deal with a terrorist attack in the UK.

At least 16 separate pieces of guidance have been sent out to key staff, covering issues ranging from how to deal with mass casualties to guidance on how to deal with smallpox or anthrax attacks.

Smallpox vaccines have been stockpiled and the NHS has supplies of antibiotics to treat people infected with anthrax or plague.

The health service also has supplies of emergency breathing equipment, protective equipment and decontamination facilities for staff.

The Department of Health has also carried out a comprehensive review of its emergency plans.

But a National Audit Office report found some hospital and ambulance trusts said they had not seen some key guidance.

It said the situation in London was particularly poor, and warned a large scale incident would "challenge the NHS".

A public information campaign on what to do in the event of an attack is to be launched this year.

Posters will include tips such as running away from poison gas or using handkerchiefs as improvised masks.