In a new revealation, a public inquiry has been told that Sikh militants had warned the Indo-Canadian community not to fly on Air India weeks before the deadly 1985 Kanishka bombing.

Former Vancouver police officer Don McLean, then part of the Indo-Canadian Liaison Team, testified before the inquiry commission that he heard through his sources around June 9, 1985 - just two weeks before the deadly bombing - that Parmar had warned congregants at the Malton temple not to fly on Air India because it would be dangerous.

McLean, testifying at the Ottawa inquiry for the second time in a month, said his team got more and more intelligence about violent Sikh separatists assaulting and intimidating moderates who spoke out against the Khalistan cause.

McLean testified the separatists 'used threats and force in an attempt to accomplish that aim. We investigated numerous assaults'.

He mentioned the February 1985 attack on Ujjal Dosanjh, now a Member of Parliament, as one of the high-profile cases.

The intimidation from the violent extremists made moderate reluctant to cooperate with police, McLean said and added, "It was just the same if the triads were involved or the Hell's Angels were involved, the same level of intimidation."

Still, he managed to gather intelligence on some key ,militants including suspected Air India mastermind Talwinder Singh Parmar, which he passed on to both Royal Canadian Mounted Police and the Canadian Security Intelligence Service.

After the bombing, McLean helped both the RCMP and CSIS with the investigation. But he said he felt marginalised as the 'token munie' (the only municipal police officer working on the case) and he soon went back to his work in Vancouver.

He criticised the way the RCMP was using standards methods, such as door-knocking, to try to get information from members of a community that feared police.

As he worked his team, he did his job differently, McLean told Major.

He learned some Punjabi, attended gurdwaras on the weekend, showed up at weddings and other community events and built trust among Sikhs who were often suspicious of police.

"As I became more involved with the community, I made sure I was available 24 hours a day, 7 days a week," McLean said.

The Canadian police largely ignored the expertise of local police in dealing with the Vancouver Sikhs he said, and added that he wasn't impressed by some of the Mounties' investigative techniques in the weeks following the attack.

"They used your usual police methods of going and knocking on doors a presenting themselves as police officers," McLean said. "(They) expected to get information that way. There was a lot of resistance to that from the community. They would prefer to talk to us."

McLean said he worked no more than a month and a half with the RCMP after Flight 182 was downed by a terrorist bomb, advising the federal force on the intelligence he had gathered, the contacts he had made and the confidential sources he had developed prior to the attack.

But he said he soon became no more than a token figure in the joint task force investigating the bombing, and felt his presence was mainly symbolic - to allow the RCMP to claim it was utilising local knowledge.