The head of the Air India inquiry Justice John Major has accused the Canadian government of trying to undercut a former intelligence official's startling testimony about what transpired in the days leading to the deadly 1985 bombing

In a pointed intervention at the hearings on Monday, the former Supreme Court Justice said that there seems to be an 'effort by the government to discredit James Bartleman.'

Bartleman, now Ontario's lieutenant-governor, stunned the inquiry last week by declaring that he had seen an electronic intercept days before the bombing that suggested Air India will be targeted by terrorists the following weekend.

The assertion contradicted two decades of repeated claims by the federal government that, despite a multitude of generalised warnings, there was never any hard and specific intelligence predicting a particular Air India flight would be in jeopardy.

The former Supreme Court justice went on to express concern that Gordon Smith, Bartleman's former boss at the Foreign Affairs Department, appeared to have aligned himself with that effort.

"You are just falling into line with the others," Major interjected as Smith was fielding questions from lawyers.

"I am not questioning your sincerity, but it is obvious that they do not like that testimony (by Bartleman). You are one of several who seem upset by that evidence," he said.