Ripudaman Singh Malik

These are the first charges ever laid in the 15-year-old investigation into the bombing, one of the deadliest in aviation history.

The plane was on its way from Toronto to Delhi via London on 23 June, 1985, when it blew up off the coast of the Irish Republic.

Mr Bagri has also been charged with the attempted murder in 1988 of Tara Singh Hayer, the editor of the Indo-Canadian Times.

Mr Hayer had reportedly agreed to be a witness against suspects in the Air India case.

Mr Hayer was left in a wheelchair by the 1988 attempt on his life. He was killed in a shooting at his home in 1998.

The Royal Canadian Mounted Police (RCMP) have not charged Mr Bagri in connection with the 1998 killing of Mr Hayer.

Second bomb

The two men have also been charged with a second bomb explosion, which occurred less than an hour later on the same day, on the ground at Tokyo's Narita Airport.

A suitcase due to be loaded on to an Air India plane from a flight from Canada blew up at the airport, killing two baggage handlers.

Ajaib Singh Bagri

The men are charged with attempted murder against passengers of that Air India flight, which was going to Bangkok.

Police had already established a link between the two attacks, which they had put down to Sikh extremists in Canada wanting to avenge the 1984 attack by Indian troops on the Sikh holy shrine, the Golden Temple.

Expensive investigation

The investigation has been one of the longest and most expensive in Canadian history at $15m.

It has also been fraught with difficulties, with bickering between different arms of the investigation team.

Flight recorders were taken to India

Vast amounts of evidence were studied in the investigation - some from the Irish Sea and Japan, some from recordings made by intelligence sources.

Several times in the past 15 years police have said they were on the verge of laying charges.

Members of Canada's large Sikh community have already said they are relieved by Friday's announcement.

Police say more arrests and charges may follow.

The western Canadian province of British Columbia has a large Sikh community which at the time of the bombings included supporters of the militant group Babbar Khalsa.