Canada’s spy service destroyed a Cold War dossier on Pierre Trudeau in 1989 instead of turning it over to the national archives, The Canadian Press has learned.

The Canadian Security Intelligence Service says the secret file on the former prime minister was scrapped because it fell short of the legal threshold for retention by either the service or the archives.

News of the decision to purge the file, which is coming to light only three decades later, has stunned and disappointed historians.

“It’s just outrageous, there’s no other word to describe it,” said John English, who wrote an acclaimed biography of Trudeau. “It’s a tragedy that this has happened, and I think the explanation is weak.”

Steve Hewitt, who has spent years chronicling the country’s security services, called the destruction “a crime against Canadian history.”

“This wanton destruction cries out for parliamentary intervention to ensure that historically significant documents held by government agencies are preserved instead of being made to disappear down an Orwellian memory hole,” said Hewitt, a senior lecturer at the University of Birmingham.

The Trudeau file was among hundreds of thousands the Mounties inherited in the 1980s after the RCMP Security Service was dissolved following a series of scandals.

In a bid to uncover subversives out to disrupt the established order, RCMP spies eyed a staggering variety of groups and individuals, from academics and unions to environmentalists, peace groups and even politicians.

In 1988, James Kelleher, the federal minister responsible for CSIS at the time, directed the spy service to sort through the resulting heap of files.

Some RCMP records — including voluminous files on Quebec premier Rene Levesque and NDP leaders David Lewis and Tommy Douglas — were sent to the national archives.

In addition, guidelines and regulations set by the archives “are always followed when determining whether CSIS holdings contain archival value.”

CSIS declined to elaborate on the rationale for purging the Trudeau file.

However, when destruction of the Pearson and Diefenbaker files came to light seven years ago, the spy service noted they were presumably compiled at the height of the Cold War with the Soviet Union.