Canada's [Images] spy agency was neither cooperative nor forthright during the probe into the Kanishka bombing case, a former Crown prosecutor has said terming as "incompetent" its act of erasing wiretap tapes of a key suspect in the case.

James Jardine submitted before the Air India inquiry commission on Tuesday that he was frustrated for months by the reluctance of Canadian Security Intelligence Service to protect the tapes of Talwinder Singh Parmar, prime suspect in the June 1985 Air India bombing that killed 329 people, mostly of Indian origin.

CSIS decided the tapes, containing details of Parmar's telephone calls, had no evidential value and routinely erased them without police ever getting a chance to review them, Jardine who is now a British Columbia Provincial Court judge told Commissioner John Major.

He wrote a brief note then stating his disbelief in the act of the agency. "In the brashness of the moment, I wrote inconceivable, incomprehensible, indefensible, incompetent," he said.

Earlier, former superintendent of the Royal Canadian Mounted Police Lyman Henschel also told the commission that the central intelligence agency denied him access to the tapes.

Inquiry counsel Mark Freiman examined documents showing repeated requests by the RCMP and Jardine's prosecution team to get details of surveillance and wiretap tapes that could have provided evidence against Parmar, Inderjit Singh Reyat and other suspects in the case.

Jardine assisted the Air India Task Force beginning in July 1985, when he was assigned to the case as a prosecutor.

He then felt there must be wiretaps because he knew that CSIS had surveillance on Parmar and told RCMP investigators, with whom he had a great relationship that, "If there are watchers, there will likely be wires."

"I certainly made it clear what I required to mount a successful prosecution. So the RCMP set out on a frustrating quest to get CSIS to hand over tapes and get access to surveillance and notes of the tapes," he added.

Parmar, the head of the militant group Babbar Khalsa, was arrested by the RCMP shortly after the attack, but was released for lack of evidence. He later left Canada, and in 1992 was shot dead by police in Punjab.

Tape erasures by CSIS were a significant issue in the trial of Inderjit Singh Reyat, the only person convicted in relation to the bombing.

A Parmar associate, he was found guilty on a reduced charge of manslaughter in  2003 and was sentenced to five-year imprisonment.

Air India Flight 182 exploded near Ireland as it was en route from Canada to India.

The blast killed 329 people, including 280 Canadians.