The BBC's Graham Satchell: "Human volunteers to test chemical weapons"

The inquiry follows claims made by another former serviceman, who said his health was ruined by the same tests at the Ministry of Defence's chemical and biological research base at Porton Down in Wiltshire.

It is the first time that the Defence Evaluation and Research Agency (Dera), which runs the Porton Down facility, has faced a criminal investigation.

Tam Dalyell MP :"In 1968 there were rumours things had gone wrong years before"

Officers will examine the death of Ronald Maddison following experiments with the nerve gas Sarin performed on volunteer servicemen in May 1953.

Human guinea pigs

Gordon Bell says servicemen were tricked into the tests

Mr Bell, 61, claims servicemen were tricked into testing nerve gases after being told the trials were tests for ''common cold research''.

Ronald Maddison was given a massive dose of Sarin dripped through his clothing with the purpose of finding out just how much it would take to kill a man in uniform,'' he told the BBC.

Andrew Hosken explores Porton Down's past

Sarin was used in the 1995 Tokyo subway gas attack by the Aum Shinrikyo Supreme Truth sect in which 12 people died and 4,000 were left sick.

Wiltshire Police confirmed they were investigating Mr Bell's allegations about his poor health and the circumstances surrounding the death of Ronald Maddison.

The deputy head of Wiltshire CID, Detective Superintendent Gerry Luckett, told the BBC that charges could include administering a noxious substance, assault and corporate manslaughter.

Cover-up claim

Porton Down has not responded to the police announcement, but the Defence Evaluation and Research Agency, part of the MoD, said it was aware of the investigation.

The Technical Director of Porton Down, Dr Rick Hall, says the establisment is now very open

A statement said: "We are more than willing to make available to the police our archives inherited from that period."

But Mr Bell says that many records about the tests have been destroyed.

In all, 300 ex-servicemen claim to have disabilities ranging from breathing difficulties to kidney complaints as a result of the tests.