Canada's long-running Air India trial entered its final stages on Tuesday, as the defense began closing arguments by accusing a key witness of lying about what she knew of history's deadliest bombing of a civilian aircraft.

Lawyers for Ripudaman Singh Malik told the court in Vancouver that prosecutors also failed to prove the wealthy businessman had the political motivation to be involved in a conspiracy by Canadian-based Sikh militants.

"It is inconceivable that anybody would have participated in this crime without a political motive," David Crossin told the court.

Malik and Ajaib Singh Bagri are charged with the mid-air destruction of Air India Flight 182 off the coast of Ireland in June 1985, killing 329 people. The plane was destroyed as it approached London for a refueling stop on its flight from Canada to India.

The two are also charged with an attempt to bomb a second Air India jet over the Pacific Ocean at the same time. Investigators say that bomb exploded prematurely, killing two airport workers in Tokyo.

Police allege the bombings were revenge attacks for the Indian Army's bloody 1984 storming of Sikhism's Golden Temple in Amritsar.

Crossin said the case against Malik "stands or falls" based on the credibility of a former confidant who said he told her details of the bombing in 1996 and 1997.

"It is our position that the evidence (of the witness) is neither reliable or credible," Crossin said.

The witness testified for several weeks, often talking emotionally about death threats she said she got because of her knowledge. The court has banned the media from disclosing her name.

Eddie Madon, whose father was killed in the Flight 182 explosion and who has attended much of the trial, said he did not think the defense would hurt the witness's credibility.

"She had nothing to gain and everything to lose by telling her story. Her life is ruined," Madon told reporters outside the courthouse.

At least one of Malik's children was also in the audience on Tuesday to watch the trial that is being held in a high security courtroom that was built specially for the case.

TRIAL HAS LASTED OVER A YEAR

Malik and Bagri are being tried jointly before a British Columbia Supreme Court judge, but are using separate defense teams. Bagri's lawyers, and prosecutors, are scheduled to deliver their closing arguments later in the month.

The trial's opening arguments began in April 2003. The evidence has included explosives experts who gave the judge a tour of Flight 182's wreckage, which has been partially reconstructed in a secret warehouse in Vancouver.

A third defendant in the case, Inderjit Singh Reyat, pleaded guilty to a reduced charge before the trial started. He was called as a prosecution witness, but told the court he knew nothing about the alleged conspiracy.

Investigators allege the mastermind of the plot was Talwinder Singh Parmar, a founder of the Sikh militant group Babbar Khalsa, who was killed by police in India in 1992.

The police investigation of Flight 182 has been marked by controversy, including a decision by Canada's spy agency to destroy wiretap evidence about the defendants.

Malik and Bagri, a Kamloops, British Columbia, sawmill worker, have been in custody since October 2000.

(Reuters)