Ronald Maddison: Sarin B was dripped on to his arm

It is claimed that 20-year-old Mr Maddison died after 200mg of the deadly nerve agent sarin was dripped on to a patch of uniform taped to his arm at Porton Down, a chemical and biological defence establishment on Salisbury Plain.

The original inquest into his death was held 48 years ago behind closed doors, where a coroner concluded he died of asphyxia. The coroner's report was never released and the only relative allowed into the inquest was the airman's father, who was sworn to silence under the Official Secrets Act.

Human 'guinea pigs'

But following complaints from other service personnel, who claim they were used as "guinea pigs" in germ warfare experiments, Wiltshire Police launched an investigation into the circumstances of the Maddison case.

For the past fortnight, the local coroner has been examining a fresh dossier on Mr Maddison's death, compiled by detectives after a two-year investigation into more than 70 deaths among Porton Down volunteers.

Newsnight said it had been given access to previously unseen Ministry of Defence (MOD) documents about the experiment on Mr Maddison.

The tests also involved Michael Cox and the papers revealed details of an enzyme in his blood that was badly affected by sarin. For Mr Maddison, the reaction was twice as severe, the programme said.

'No comment'

In a statement, the MOD said it was unaware of the coroner's conclusions and could not comment.

"We have, from the outset, been open and co-operating fully with the Wiltshire police investigation. We will continue to do so in the future and with the coroner, if required," a spokesperson said.

The Ministry of Defence's chemical and biological weapons research centre has tested 3,000 service personnel in human volunteer experiments since 1945.

More than 300 ex-servicemen claim to have suffered disabilities ranging from breathing difficulties to kidney complaints as a result of tests carried out at the centre run by the Defence Evaluation and Research Agency (Dera).