Terrorism fears are spreading in the United Kingdom following the suicide bombings in Istanbul and security experts warn that London continues to remain on the hit list of terrorists.

The British public's memory is still raw from the television images of the Istanbul attacks, which killed 27, including UK Consul general Roger Short, and wounded 450.

As the full horror of the attacks filter through, British Prime Minister Tony Blair is being urged to upgrade security measures at home.

If Blair and the rest of his cabinet agree to place the country on an unprecedented peacetime 'red alert', this would result in tougher security checks across the country, including extra powers for police and other security agencies to increase surveillance, telephone tapping and detain terrorist suspects.

Following the September 11 attacks, the British government rushed through a legislation giving security agencies the right to detain indefinitely suspected terrorists, as well as monitor bank accounts, phone calls and emails.

For a country so proud of its hard won political freedoms, such a move amounted to a massive setback for civil rights.

Some further erosion of rights and freedoms now seems inevitable following last week's revelation by the UK's top policeman, London Metropolitan Police Commissioner Sir John Stevens, that his officers had foiled an unspecified number of terrorist attacks on London.

Sir John's disclosure on a BBC radio broadcast has been backed up by UK Home secretary David Blunkett, who said on Saturday that he was "sick and tired" of people pretending there was not a threat from terrorists.

Blunkett has initiated discussions with senior intelligence and security advisers about boosting the UK's anti-terrorism defences still further following reports that a potential poison attack was blocked last year when an unnamed group tried to purchase half a tonne of toxic chemicals from a British company that reported the attempted transaction to the police.

A spokesman for the company involved, Amersham Biosciences, says the "Islamic community" funded the group that placed the order.

Security sources say the attempt to buy 500kg of saponin could have ended up in widespread poisoning if the substance was mixed with ricin or another toxin and smeared in public places.

Poison attack fears are being circulated in tandem with other reports that terrorists from North Africa and Saudi Arabia have been making suicide car bomb 'dummy runs' against banks, commercial centres and other vulnerable civilian targets within the UK.

According to a report in London's Sunday Times the terrorists are said to be part of two Al Qa'eda cells preparing to carry out a "spectacular" attack on the British mainland.