Inderjit Singh Reyat will be tried with the other two defendants (pic courtesy of CBC)

The trial had been scheduled to begin in February in the Canadian city of Vancouver.

Lawyers for one of the accused, Inderjit Singh Reyat, had asked to have their client tried separately at a later date.

But Justice Bruce Josephson has rejected that request.

In a 25-page ruling made public on Wednesday, the judge said the interests of justice required a joint trial of all three accused.

First-degree murder

Mr Reyat is on trial along with Vancouver businessman Ripudaman Singh Malik, and mill worker Ajaib Singh Bagri.

They are accused of planting the bomb that brought down Air India flight 182 off the coast of Ireland, killing all 329 people on board.

Mr Malik was charged more than a year ago

They face charges including first degree murder, attempted murder and placing a bomb on an aircraft.

Mr Bagri and Mr Malik were arrested and charged more than a year ago, but Mr. Reyat was not charged until this June and his lawyers were appointed in September.

Given the size and scope of the trial, his lawyers had argued that they needed more time to prepare a case.

But the judge said while he understood the need for more preparation time, justice required that all three accused be tried together.

And so he has decided to push the start of the case back by nine months.

When it does begin, the Air India trial will be by far the largest case ever heard in Canada.

There could be as many as 1,000 witnesses, it could last two years or more and the courtroom itself will need to accommodate about 20 lawyers.

There will also be dozens of journalists and perhaps hundreds of onlookers.

The Canadian government has offered to pay the expenses so family members of people who died on the flight can attend portions of the trial.

Sikh militants

Flight 182 was on its way from Toronto to Bombay with a stop in London when it blew up off the coast of Ireland.

Most of the passengers were Canadians.

Police believe that the bomb was hidden in luggage which was sent from Vancouver to connect with flight 182.

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.

Authorities believe the bombings were carried out in retaliation for a bloody 1984 attack by Indian troops on the holiest of Sikh shrines, the Golden Temple in Amritsar in India.