A government-commissioned investigation into suspected wrongdoing by the Royal Canadian Mounted Police concluded today in a scathing report on past police conduct that domestic security operations be taken out of the hands of the national force.

The three-member commission, whose four-year, $10 million investigation was the most extensive ever undertaken of Canada's security forces, also recommended that charges be placed against Mounted Police officers for alleged illegal conduct in the early 1970s.

The allegations included removal of documents from a left-wing news agency, surreptitious copying of membership lists of a political party, the taking of dynamite from a locked warehouse and the burning of a barn to thwart a meeting between subversive groups.

Today's report brought the first public confirmation that Prime Minister Pierre Trudeau did have some knowledge that Mounties officers were involved in "illegal things" for 20 years prior to 1970.

But he inquiry board, known as the McDonald Commission after its chairman, Justice David McDonald, left unresolved one of the most controversial issues associated with the recent scandals in the force: whether, as Trudeau's critics charge, he and his government ministers knew that the Mounties' security service was involved in questionable activities but failed to put a halt to them.

A spokesman for Trudeau's Liberal Party government, which periodically has been under severe attack by its critics as revelations of wrongdoing in the Mounties have emerged in recent years, immediately announced plans to comply with the commission's main suggestions. The government was setting up a task force to handle the transfer of intelligence and security activities to a new agency, the Canadian Security Intelligence Service, the spokesman said.

Today's report said Trudeau was told at a Cabinet committee meeting in September of 1970 that the Mounties had been engaged in questionable activities.

But the commission added that there was no evidence that Trudeau was given specific details of illegal acts and apparently did not ask.

The report provided potential ammunition for those who have been claiming for some years that the Trudeau government has been involved in a coverup of the Mounties' activities. "There is no doubt in our minds that an attempt was made by senior members of the Mounted Police to have aspects of the question of illegal acts discussed at the highest level of government," the report said. An aide to Trudeau said the prime minister would have no comment on that aspect of the report.

Set up in 1977, the McDonald Commission focused on Mounties' operations during the early 1970s, a period of extreme political tension that followed a kidnaping by extremists of the Quebec Liberation Front and other nationalist-inspired violence.

After examining the allegedly illegal operations of the Mounties, the McDonald Commission was harshly critical of many senior officers on the force in the 1970s. The commission said the officers misled a session of Cabinet ministers, and therefore misled Parliament and the public, about illegal acts committed by members of the force.

The commission said that the most serious charge was probably that there was a "willingness on the part of members of the force to deceive those outside the force who have some sort of constitutional authority or jurisdiction over them or their activities."

A government spokesman said authorities will have to study the recommendations that charges be laid against Mounted Police officers.