Former Vancouver Police Department officer Rick Crook told the Commission that an unidentified Sikh man facing unrelated charges told authorities in October 1984 of a plot "to place a bomb on an Air India plane" in a bid to get leniency from the courts.

The plan was "to strike at the government of India" for its attack on the Golden Temple at Amritsar, the suspect said in a police interview, according to a transcript read by Crook at the inquiry which resumed Monday.

"There was a plan to place a bomb on an Air India plane in Montreal," Crook testified, adding that he learnt in an interview with the suspect that an "Air India 747" leaving from Montreal would be targeted.

The suspect said "a small group of people" were involved in the plot, but did not identify them, he said.

Crook, who was part of the department's Indo-Canadian community liaison team, said he was mostly unfamiliar with Sikh extremism in Canada at the time and questioned the informer's honesty.

Still, the information was passed on to the fledgling Canadian Security Intelligence Service, he said, noting the case was "beyond (his department's) capabilities" to investigate.

The blast killed 329 passengers and crewmembers, including 280 Canadians, off the coast of Ireland in the world's worst airline attack prior to the September 11, 2001 attacks in the United States.

Prosecutors blamed radical orthodox Sikh immigrants to Canada, saying the bombing was payback for the Indian government's 1984 operations at the Golden Temple.

But the only person jailed over the airline attack was bomb-maker Inderjit Singh Reyat, who now faces perjury charges over his testimony at the trial of two men acquitted in the plot in 2005.

The alleged mastermind of the plot, Talwinder Singh Parmar, was killed in a police shootout in India in 1992.

According to reports, other warnings came from the Indian government and Air India itself, which told Canada's federal police three weeks before the bombing that Sikh extremists in Canada were planning to bomb Air India flights.

The inquiry heard three weeks of emotional testimony last fall from the victims' families recounting their personal ordeals and frustrations over the last two decades. But there have been hardly any hearings since then on the details of what happened.

Most of the delay can be attributed to haggling between commission counsel and lawyers for the federal government over how much of the documentary trail and oral testimony from here on will be public and how much will remain behind closed doors for reasons of national security.