Canada needs a security tsar to avoid repeating the "cascading series of errors" by intelligence and police agencies that led to the bombing of Air India Flight 182, an inquiry into the case said on Thursday.
The scathing report cited "turf wars" that prevented authorities from stopping the 1985 attack, which killed 329 people, and hamstrung efforts to catch those responsible for history's deadliest bombing of an airliner.
"A cascading series of errors contributed to the failure of our police and our security forces to prevent this atrocity… various institutions and organisations did not fulfil their responsibilities," said former Supreme Court Judge John Major, who headed the inquiry.
The more than 3,000-page report, which is reminiscent of the findings of a US inquiry into the failure to prevent the 9/11 attacks on New York and Washington, chides the Canadian government for claiming it has since fixed the security lapses.
"This commission rejects that position," Major said.
A suitcase bomb destroyed Air India Flight 182 off Ireland's Atlantic coast on June 23, 1985, while the aircraft was en route from Canada to India via London. Many of the victims were Canadian citizens returning to India to visit relatives.
The attack is widely thought to be the work of western Canadian-based Sikhs fighting for an independent homeland in India, who wanted revenge for India's deadly 1984 storming of the Golden Temple in Amritsar, Sikhism's holiest shrine.
An attempt to blow up a second Air India flight over the Pacific at the same time, instead killed two airport workers in Japan when that bomb exploded prematurely. The men who put the suitcase bombs on the planes in Vancouver did not get on the aircraft.
The media reported details of an alleged plot shortly after the bombings, but it took police about 15 years to charge anyone for the attack. A judge eventually found two men not guilty because of a lack of evidence.
The only man convicted in the case pleaded guilty to a lesser charge, with prosecutors acknowledging they did not have the evidence to convict him of murder.
Victims' relatives have long complained that police, as well as Canada's spy agency, ignored information about the plot that could have prevented the bombing, and then destroyed evidence in a botched investigation.
Major, who highlighted what he said were the poor relations between the Royal Canadian Mounted Police and the Canadian Security Intelligence Service spy agency, said the prime minister's national security adviser needs more powers.
"This is a crucial and fundamental requirement to achieve better co-ordination across the many agencies that have national security responsibilities," he said in prepared remarks to reporters.
The report also calls for changes to Canada's court system to make it easier to handle large terror-related trials, and for better protection of key witnesses. One witness in the Air India trial was murdered before it began.
Prime Minister Stephen Harper, who launched the inquiry in 2006 after the Air India trial, said the government took the report very seriously and will study the recommendations.
"It is a damning indictment of many things that occurred before and after the tragedy that, as I said, we are determined to avoid in the future," Harper told a gathering of victims' relatives on Thursday.
Relatives of the victims said the report addressed most of their concerns and they hope the government will implement the recommendations.
"It confirms what the families suspected while asking for the inquiry that it was not a sheer accident. It was a compounding of mistakes after mistakes after mistakes," said Bal Gupta, whose wife was killed in the bombing.
Harper said the government would react "positively" to suggestions that victims' relatives need an apology, and to Major's recommendation that they receive compensation.
Major also used his remarks to chide the Canadian public for ignoring "this Canadian atrocity".
"For too long the greatest loss of Canadian lives at the hands of terrorists has been somehow relegated outside of the Canadian consciousness," he said.