A prosecution witness in the Air-India Kanishka bombing trial altered and burned some pages of her diary after her husband accused her of "setting up" the main accused, Ripudaman Singh Malik, Canadian police told the supreme court.

The woman, whose name was not revealed under a direction from the court, used to work for Malik.

Her husband, who got angry when the police subjected her to a lie detector test, "felt she should not cooperate with police further", Corporal Douglas Best of the Royal Canadian Mounted Police said in his testimony on Thursday.

The witness, who is under police protection, is expected to tell the court that Malik confided to her details of the bombing.

Best said the woman kept a detailed journal of her conversations with Malik, some pages of which were provided to the police on November 7, 1997. She gave more pages three days later.

However, the police did not seize the entire journal until June 1999.

After Malik's defence lawyer Bill Smart pointed out discrepancies in the dates in the diary, Best confirmed that in some instances pages in the journal seized by the police in 1999 were not identical to copies of those pages that she provided to the police 19 months later.

Best told the court that the woman wrote new material on some pages in 1999.

According to the prosecution, conviction in the case depends on the credibility of the woman's evidence.

Malik and Ajaib Singh Bagri are charged with the murder of 329 peopled killed in a midair explosion aboard the Air-India flight on June 23, 1985.

They also face murder charges for the death of two baggage handlers at Japan's Narita airport about 54 minutes later.