TORONTO -- -- Canada's opposition parties have charged that the government bungled investigations into alleged Sikh terrorist activity and have demanded that Prime Minister Brian Mulroney fire his beleaguered solicitor general.

Opposition critics in the House of Commons charged this week that "gross negligence" by Solicitor General James F. Kelleher's department had made it unlikely that there would ever be prosecutions of suspects in the 1985 crash of an Air-India jet that plunged into the Irish Sea, killing 329 passengers and crew en route to India from Toronto. Kelleher has indicated he believed a bomb was planted aboard the plane before it left Canada.

Mulroney pointedly refused to respond when Liberal and New Democratic Party critics questioned whether the prime minister still had confidence in his solicitor general.

On Friday, Mulroney's office had abruptly announced the removal of T. D'Arcy Finn as head of the Canadian Security Intelligence Services, one of the two investigative agencies in Kelleher's department. The announcement came after government lawyers admitted in court that the agency had used "inaccurate and unsubstantiated" information to obtain a wiretap order against a British Columbia Sikh two weeks after the Air-India crash.

Although the man, contractor Harjit Singh Atwal, was not charged in connection with the crash, he and four other Sikhs were jailed a year later on charges of conspiring to murder an Indian official during a visit to Vancouver Island in May 1986. The key evidence against Atwal was from wiretaps installed shortly after the Air-India crash.