Saskatchewan politicians have passed a motion calling on the federal government to release security files on former premier Tommy Douglas.

The motion was proposed by the opposition New Democrats last month. It came to a vote in the provincial legislature Thursday morning and passed unanimously.

Douglas was the subject of RCMP surveillance for decades, even as he served as premier of Saskatchewan and later as leader of the federal CCF, which became the NDP.

The federal security agency CSIS inherited the surveillance files after it took over the RCMP's security responsibilities.

Dwain Lingenfelter, leader of the Saskatchewan NDP, said the Douglas files should be released.

"The normal process is that a certain number of years after the death of an individual who they have files on, they're automatically released unless there's some substantial reason … why they shouldn't be released," Lingenfelter said.

"We could be convinced [otherwise]. But at this point we have no reason at all to believe that there's anything in the files that would make them a reason not to release them."

A letter will be sent to the Prime Minster's Office from Saskatchewan, asking for the information to be released.