PORTON Down has paid tribute to a former head of microbiology at the establishment, biological weapons expert Dr David Kelly, who was found dead on Friday.

Dr Kelly (59), the source behind the BBC allegation that the government "sexed up" its first intelligence dossier on Iraq, was based at the then Chemical Defence Establish-ment at Porton Down (now the Defence Science and Techno-logy Laboratory) between 1984 and 1992.

Graduating from Oxford University with his DPhil in 1971, Dr Kelly was just 40 when he left the Oxford Institute of Virology to become head of microbiology at the government site near Salisbury - a move he described as "the best decision of my life".

In this very senior role, he led a team of scientists who carried out research into protection against and detection of agents that could be used in biological warfare.

This included the development of devices to detect such biological warfare weapons as anthrax, botulism, smallpox and plague, and vaccines to protect those engaged in the defence of the UK.

A DSTL spokeswoman said: "He was a well-respected member of the team and had been seconded to central MoD for the past ten years.

"Obviously, we are very shocked at the news and our thoughts are with his family at this very difficult time."

Salisbury resident and anthrax expert Dr Peter Turnbull, who formerly worked at Porton Down's Centre for Applied Microbiology and Research and is currently on a private assignment in the United States, said: "David Kelly and I started work at Porton Down at the same time.

"He was superintendent of the then defence microbiology division of the Chemical Defence Establishment, and I knew him through working on various contracts from his division.

"His death is a deeply tragic end to a most illustrious civil service career. He was a fine sci-entist with absolute integrity.

"If, as stated in The Washington Post, he said an intelligence dossier had been 'sexed-up' to make a more convincing case for the war in Iraq, I would believe it absolutely."

Dr Kelly's identification as a BBC 'mole' came about after he volunteered to his bosses at the MoD that he had been in contact with BBC journalist Andrew Gilligan.

Defence secretary Geoff Hoon then wrote to the BBC, asking the corporation to confirm or deny whether Dr Kelly was at the centre of a bitter row between Downing Street 'spin doctor' Alastair Campbell and Mr Gilligan over a report by the journalist.

Dr Kelly gave evidence to the Commons' foreign affairs select committee, at which he said that, considering the nature of the report as presented on Radio Four by Mr Gilligan, he felt he could not have been its primary source.

The report had claimed that a dossier on Iraq had been "sexed-up" to boost public support for war in Iraq.

The BBC later confirmed that Dr Kelly was the primary source for its report.

Dr Kelly appeared fraught and somewhat nervous during questioning and his family later said the ordeal had placed a great strain on him.

He left his home in Southmoor, Oxfordshire, on Thursday afternoon, telling his wife he was going for a walk.

His body was discovered five miles from his home on Friday, with a cut across one wrist.

A judicial enquiry will now be held into the circumstances surrounding Dr Kelly's apparent suicide.