A FORMER MI5 agent who blew the whistle on an attempt to bug the Pakistani high commission has fled to the Continent and is threatening to reveal more about the aborted spying operation.

He claims to have a dossier of evidence ?? including documents and photographs ?? revealing details about MI5??s espionage techniques and what information it was trying to obtain about Pakistan. The man, a building contractor who was codenamed Notation, left Britain this month, shortly before The Sunday Times revealed the spying operation.

David Blunkett, the home secretary, was said by aides to be furious about the botched spying operation and the leak. He has denied signing warrants authorising the espionage attempt. That appears to contradict claims by Notation who said he received detailed assurances from MI5 that the home secretary had issued warrants.

He said: ??Claire, my handler, told me on several occasions how MI5 sought and obtained the warrants from Blunkett.??

Notation is now being sought for questioning. MI5 wants to prevent him revealing further secrets. A Home Office source said he may face prosecution under the Official Secrets Act.

Notation was recruited by MI5 in 2001 to provide access to the Pakistani high commission in Belgravia, London, during restoration work.

Posing as building workers, members of MI5 entered the building, stole codes for sending secret messages and planned to plant listening devices and remove documents. The operation was aborted after Notation became worried that his role could be exposed. He later wrote to the parliamentary intelligence and security committee, saying he was concerned for his safety.

The affair has caused a diplomatic rift between London and Islamabad. Pakistan said it had sent its own experts to debug the high commission. ??We have already dispatched people; they are in Britain,?? Khurshid Kasuri, Pakistan??s foreign minister, told a televised news conference in Islamabad last week.

The Conservatives are demanding a House of Commons statement from Jack Straw, the foreign secretary, and said the botched operation had severely damaged Anglo-Pakistani relations.

Pakistan continued to put pressure on Britain last week. Kusuri said he had demanded an explanation for the spying during a meeting with Straw in London. Straw told him he was forbidden by law from commenting on intelligence matters. Kusuri said there was now ??a question of confidence?? between the two countries.

Friends of Notation are growing concerned about him. He was once sectioned under the Mental Health Act and treated in a specialist clinic. The head of the west London building firm for which he worked said Notation had simply vanished together with his girlfriend.

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