OTTAWA -- The federal information watchdog is conducting a systemic investigation of the "ongoing failure" of the national archives to provide timely responses to requests from the public for historical spy files.

Information commissioner Caroline Maynard says a chronic concern underlying the probe is Library and Archives Canada's difficulty in vetting decades-old, but still highly classified, intelligence files for release.

Matters are complicated by a long-standing requirement that the archives consult the Canadian Security Intelligence Service before disclosing these records, adding significant delays to the processing of requests.

Library and Archives holds more than 7,000 containers of CSIS records, most of which were created by the spy agency's predecessor, the RCMP security service.

Public requests for these archival records -- which include everything from old files on suspected subversives to assessments of Cold War-era threats -- must be processed under the Access to Information Act.

Analysts comb through the pages and material considered sensitive, however old it might be, is stripped from the documents prior to a release.

This report by The Canadian Press was first published May 18, 2021.