Mr Maddison thought he was helping to cure the common cold

Ronald Maddison, from Consett, County Durham, died at the MoD's laboratories on Salisbury Plain in 1953.

The delay comes as a powerful committee of MPs said the government relies too much on Porton Down to protect the country from a biological terrorist attack.

The Commons Science and Technology Committee praised the MoD's research facilities, but recommended that a new "Centre for Home Defence" is built.

'National security'

This could train fire, police and ambulance staff, and look at the defence of rail, airport and transport systems.

Committee member and MP for Salisbury, Robert Key, told the BBC: "The report says we need a change of attitude. We should be more open about security."

A full hearing into what led to Mr Maddison's death was due to begin at Trowbridge in Wiltshire on 18 November, and last six to eight weeks.

RAF engineer Ronald Maddison was 20 when he took part in what he thought was an experiment to find a cure for the common cold in May 1953.

The Lord Chief Justice Lord Woolf quashed the original inquest verdict of death by misadventure last year and ordered a second inquest to be opened.

The original inquest was held in secret "for reasons of national security".