©Tammy Hoy/Canadian Press

In this artist's sketch, Mohammad Momin Khawaja, centre, is shown in an Ottawa courtroom in June 2008 at the beginning of his trial.

The Crown's star witness in the trial of the first person charged under Canada's Anti-terrorism Act told an Ottawa court Wednesday that he never discussed a fertilizer bomb plot with the accused.

The admission at the trial of Mohammad Momin Khawaja came during the defence's cross-examination of Mohammad Junaid Babar, a former al-Qaeda operative turned police informant.

Khawaja, a 29-year-old Canadian of Pakistani descent, faces seven Canadian charges in a failed 2004 plot to bomb a London nightclub, a shopping centre and several public sites. He has pleaded not guilty and denies being part of the al-Qaeda-inspired plot.

Babar, an FBI informant who has admitted to setting up terrorist training camps in Pakistan, testified he wasn't even aware of the plot when he met Khawaja on the way to one of the training camps in 2003.

Khawaja's defence team tried to discredit Babar's testimony, highlighting discrepancies between what Babar told a British court two years ago and what he told a Canadian court last week, the CBC's James Cudmore reported from the trial.

Those attending training camp tricked: defence

Defence lawyer Lawrence Greenspon suggested the men who attended the training camp in northern Pakistan were tricked by British conspirator Omar Khyam into believing they were going to fight in Afghanistan, not participate in a bomb plot in Britain.

"The trick was to talk about Afghanistan, train these guys for Afghanistan, and not tell them about the U.K. bomb plot," Greenspon told the court. Babar agreed.

During his questioning of the witness, Greenspon tried to portray Babar as a man who would say anything in order to save his own skin, the CBC's Cudmore said.

But Babar took issue with that assertion, insisting that "hoping and actually happening are two different things."

Babar, who has already pleaded guilty to terrorist offences in a U.S. court, faces a maximum 70 years in prison for his role in several plots, including a plan to detonate a fertilizer bomb in London.

But he could be out of jail in as little as a year, after he agreed to testify in two trials in the United Kingdom and Khawaja's trial in Ottawa. Khyam and four other men were convicted by a British court in 2007 for participating in the failed bombing plot.

Babar testified on Friday that Khawaja attended the same terrorist training camp as Mohammed Siddiqui Khan - the ringleader of the 2005 London transit bombings that killed 52 people.

Khawaja was a software developer working for the federal Foreign Affairs Department when he was arrested at his Ottawa home in 2004 as part of a British and Canadian investigation. He has been held in custody since then.

The trial, presided over by a judge alone, is expected to run until October or November.