The perjury trial for the only person convicted in the 1985 Air India bombing that killed 329 people off the coast of Ireland has begun in Vancouver, Canada.

Canadian Sikh Inderjit Singh Reyat was charged with perjury in 2006. Prosecuting lawyer Len Doust told jurors.

Thursday in his opening statement that Reyat already pleaded guilty to supplying bomb parts in one of two bombings in 1985.

Reyat has been accused of lying during the trial of the two key convicts Ajaib Singh Bagri and Ripudaman Singh Malik in September 2003, which resulted in their acquittal in 2005.

While the prosecutors don't plan to call witnesses against Reyat, they will have the jury listen to Reyat's testimony in court in 2003 and read statements he gave before appearing as a witness.

Reyat had pleaded guilty to helping construct the bomb, and was called as a prosecution witness in the murder trial of Ripudaman Singh Malik and Ajiab Singh Bagri.

On the witness stand, Reyat denied knowing why he was asked to build a bomb, what the target was, or ever asking the name of an unidentified man who spent a week in Reyat's home constructing the bomb.

The judge who found Malik and Bagri not guilty of murder and conspiracy, called Reyat an "unmitigated liar".

The bombing of Flight 182 is regarded as one of the deadliest involving a commercial airliner.

Police have said Sikh extremists living in Canada were behind the attack that was carried out as an act of revenge for the the Indian Army's storming of the Golden Temple in Amritsar in June, 1984.

The plotters also planned to destroy an Air India flight over the Pacific Ocean at the same time, but that bomb instead exploded in Japan's Narita airport, killing two baggage handlers.

The Canadian government formally apologized in June to families of the Air India victims, saying authorities failed in their duty to disrupt the plot and prevent the tragedy.

The perjury trial is expected to run into next week. (ANI)