An informer said that days before a bomb exploded on an Air India jetliner in 1985, killing 329 people, he tipped Canadian police that Sikh terrorists planned such an attack. In Ottawa, opposition Parliament members called on Solicitor General James Kelleher to resign in the wake of the report. Kelleher acknowledged that Paul Besso, 27, had been an informer for the Royal Canadian Mounted Police, but he said there was never any specific threat against the Air India jet, on a flight from Toronto to Bombay. There have been no arrests in the case. The director of the Canadian Security Intelligence Service resigned Sept. 11 after the agency said it bungled the wiretap in another Sikh investigation.