The tragic Kanishka bombing that killed 329 people in 1985 could have been averted had a bomb-sniffing dog searched the Air India plane before it left Canada, a former police officer has said.

The Air India Flight 182, which exploded off the Irish coast, was not alerted of the bomb threat and allowed to leave Canada before a bomb-sniffing dog could search the plane and its luggage, Serge Carignan, a former dog handler with Quebec's provincial police, submitted on Wednesday before the inquiry commission presided over by Justice John Major.

Carignan believed he could have found the explosives but the plane had already left the Montreal airport by the time he arrived to check it. "I've always wondered why, if I was called to search an airplane and some luggage, why did they let the airplane go before I arrived there," said Carignan.

"I did not have a chance to search that airplane. I believe that if I had a chance to search it, things might have turned out differently," he said, adding "I believe we would have found the explosives."

Carignan testified in Ottawa that he was called to Mirabel airport on June 22, 1985, hours before a bomb blew up the plane. "I was not told it was a bomb threat. I took it upon myself when I received the call that it was a bomb threat," Craigman said.

Carignan said he was told officials needed help searching a plane and luggage, and that the airport's regular Royal Canadian Mounted Police dog squad was out of the region on that date.

By the time he arrived at the airport, roughly 45 minutes later, the plane had already taken off, Carignan said.

Carignan said he didn't know why the plane departed before he got to the airport. Carignan and his sniffer dog, Arko, were taken to an airport bunker, where they searched three pieces of luggage that had been taken off the plane because they were considered suspicious.

The dog didn't find any explosives, said Carignan. The flight had a brief stop in Montreal after leaving Toronto, en route to London's Heathrow Airport and on to India.

The public inquiry, which started last year and resumed after lengthy delays on April 30, 2007, is focusing on whether there were security and intelligence failures in the investigation that followed the bombing.

Carignan discounted official reports from RCMP and Transport Canada that were provided during earlier Bob Rae probe into the disaster.

The reports said bomb-sniffing dogs checked Air India flights before they left Toronto and Montreal. "It is not true. I did not screen the flight. The only work I did was searching these three suitcases," said Carignan.

Carignan said when using sniffer dogs, cargo is usually removed from the plane and spread out on the tarmac, which didn't happen that night. "I would have expected to do that on that evening," he said.

Rae told CBC News yesterday after Carignan's testimony that it was "a nightmare of frustration" for Canadians to hear the attack could have been prevented, but wasn't.

Liberal Member of Parliament Ujjal Dosanjh said the contradictions with the RCMP and Transport Canada reports are alarming. "All of these contradictions are the making of a cover-up," Dosanjh told Canadian Broadcasting Corporation.

"This is now more than casual indifference," he added. Carignan said he was never contacted by police following the disaster and was asked to be a witness at the inquiry after his wife contacted inquiry staff last week.

Bal Gupta, who lost his wife wife Rama in the tragedy and is chairperson of the Air India Victims' Families Association, thanked Carignan for his testimony, although he said it was painful to hear about the incident.

"We suspected something like that, but what surprises me is that nobody after this tragedy ever contacted Carignan," Gupta said.

He said it showed there are still more people who have a lot to explain about that night.

"Why did the RCMP let the plane go when there was suspected baggage?" he said. "My gut feeling is that there are at least a dozen other people who know." The inquiry was called because the Air India investigation and prosecution was the costliest and one of the longest in Canadian history, yet led to no murder convictions.

Only one person was convicted in the plot. Inderjit Singh Reyat pleaded guilty to manslaughter in 2003 and received a five-year sentence.

Talwinder Singh Parmar, who died in India in 1992, who allegedly masterminded the blast and the RCMP's two main surviving suspects were both acquitted in March 2005 after a 19-month trial.