A document filed at the Air India inquiry suggests Sikh extremists may have threatened to assassinate former prime minister Brian Mulroney.

Released to the inquiry on Thursday, the previously classified document is a six-page memo dated July 15, 1986, slightly more than one year after the Air India bombing.

It was sent from a senior RCMP official, Chief Supt. J.A.N. Belanger, to Chris Scowen, a top counter-terrorism official at the Canadian Security Intelligence Agency. Stamped "secret," the version given to the inquiry had several sections blacked out.
 
In the memo, Belanger notes that the suspected mastermind behind the Air India bombing — Talwinder Singh Parmar and some of his associates — are in jail awaiting trial.

Parmar was a leading North American member of Babar Khalsa — a terrorist group dedicated to the creation of an independent Sikh state.

Letter warned of threat to PM

At the time, Parmar and his associates had been under arrest in Hamilton, Ont., on allegations they were plotting to blow up the Indian parliament and kidnap the children of Indian politicians.

The RCMP had hoped Parmar's arrest would sap the strength of a violent intimidation campaign Sikh extremists in British Columbia had been waging against Sikh moderates for several years.

But in the memo, Belanger says he's concerned the arrests could increase tensions. He says a week earlier, the Canadian government received an anonymous letter threatening to kill Mulroney.

The writer also threatens to "blast" the Toronto subway system, movie theatres and banks unless the government agrees to free Parmar and his associates. But the threats never materialized.

Parmar was freed after a trial on weapons and conspiracy charges failed to convict him.

He was never charged with the Air India bombing. He returned to India in 1991, where a year later he was killed under mysterious circumstance while in police custody.

Calls to flight tower

Air India Flight 182 exploded in the air off the west coast of Ireland on June 23, 1985. All 329 people on board were killed.

A separate luggage bomb destined for a second Air India flight killed two Japanese baggage handlers at Tokyo's Narita airport.

Additional documents released Thursday showed that after Flight 182 left Montreal, where it had stopped en route to London, the air traffic control tower at Mirabel airport received five consecutive anonymous phone calls.

The caller or callers asked whether the flight had left, when it pushed back from the gate, when it lifted off and when it was due to arrive at Heathrow.

The inquiry into the disaster, headed by retired Supreme Court justice John Major, resumed Monday with a focus on leads, tips and warnings that surfaced before the disaster.

With files from the Canadian Press