The Air India bombing inquiry has been told of a hint of coming disaster 11 days before Canada's worst mass murder.

A former Vancouver police officer, Don McLean, testified Tuesday in Ottawa about an exchange between two men he described as Sikh militants on June 12, 1985.

He quoted the first as saying: "No consuls have been killed. No ambassadors have been killed. What are you going to do? Nothing?"

The reply, he said, was: "You will see something be done in two weeks."

The conversation took place in the basement of the Vancouver-area home of a Sikh businessman who was co-operating with police in an unrelated criminal investigation, McLean testified.

About 10 people were present, including advocates of carving an independent Sikh homeland out of India, he said.

Police had bugged the basement and were listening from another room, he said.

McLean, who said he speaks "a little bit" of Punjabi, testified that he relied on the businessman's account of the exchange rather than on the surveillance tape or the notes of a Punjabi-speaking officer who eavesdropped on the conversation.

An RCMP translator who listened to the tape long afterward said there were many voices on it, but none could be heard speaking of killing diplomats or doing something in two weeks.

McLean said he passed information about the conversation on to the Canadian Security Intelligence Service and to a Vancouver officer who worked on a joint intelligence unit with the RCMP. But the RCMP filed it away as unconfirmed.

Even so, inquiry commissioner John Major said he saw no reason to doubt the businessman's version in the absence of evidence that his recollection was inaccurate.

"The statement is made by a person who was present and there's no evidence to the contrary," Major said.

McLean told Major that he connected the statement about something being done to the idea of a bomb on a plane only after all 329 people aboard Air India Flight 182 were killed on June 23, 1985.

"Once I heard of the explosion, that was the thought I had," he said.

He said the man who predicted action in two weeks was a militant named Pushpinder Singh, an admirer of Talwinder Singh Parmar, whom police later saw as the mastermind of the bombing.

Air India warns RCMP of sabotage plans

Documents submitted at the inquiry on Tuesday included a letter sent by the chief security officer of Air India warning the company's Canadian office of the "likelihood of sabotage attempts undertaken by Sikh extremists by placing time/delay devices etc. in the aircraft … or baggage.

"This calls for meticulous implementation of counter-sabotage measures," the letter said.

Air India sent a copy of that warning to the RCMP almost three weeks before the bombing but there's no indication that the force shared it with CSIS.

When Major asked why the force didn't share the information with CSIS, commission counsel Anil Kapoor said: "It simply was an oversight as I understand it."

"Oversight is hard to accept when you look at the contents," Major responded. "I mean, oversight is not filling your dog's dish with water."

"It is surprising that would be the explanation — oversight — for something as dire as that," Major said.

No one has been convicted of murder in connection with the bombing.

Parmar was arrested in November 1985 on weapons, explosives and conspiracy charges, but the charges were dropped for lack of evidence. He died in India in 1992 in what officials said was a shootout with police.

Two other men, Ripudaman Singh Malik and Ajaib Singh Bagri, were acquitted of all charges in 2005 after the costliest investigation and prosecution in Canadian history.

Bomb maker Inderjit Singh Reyat was imprisoned for manslaughter in a 2003 plea bargain.

McLean also testified about a tip he received that members of a Sikh temple near Toronto's airport were warned before the bombing to avoid flying Air India because it was unsafe.

He said he could not remember whether he got the tip before or after the bombing.