The Canadian government confirmed reports that Prime Minister Pierre Trudeau's office had ordered a secret investigation of charges that the CIA tried to rig Canadian elections, but it said no improper activities had been discovered.
The government was responding to a document that surfaced in Parliament charging that ''the CIA was extensively involved in penetrating Canadian security services.''
The document, based on information from former Howard Hughes aide John Meier, said the CIA ''was involved in financing election campaigns and individual candidates in several provinces . . . during the period 1970 to 1976.''