Highly classified documents containing details of new security measures at Hydro-Qu??bec were discovered on a subway station bench in east-end Montreal, Radio-Canada reported Sunday.

The documents, totalling some 300 pages, were found recently in an abandoned file folder by an employee of Radio-Canada, the CBC's French service.

The documents belong to a Hydro-Qu??bec security adviser, Radio-Canada said.

This was the second security breach at the Crown corporation in recent months, the Canadian Press reported

A Radio-Canada camera crew was able to enter a hydro dam last year, raising questions about security at the province's power installations.

The documents discovered in the subway station give Hydro-Qu??bec's response to the security leaks that were uncovered last year.

One document gives explicit descriptions of alarm, video-surveillance and anti-sabotage systems. The papers also reveal temporary security passwords and the home phone numbers of company executives.

Another document details how to make employee identity cards, the report said.

Hydro-Qu??bec said somebody stole an employee's briefcase while he was having dinner in a restaurant on March 10. He reported the theft to his superiors. The briefcase contained a computer and the documents found in the subway station.

Spokesman Marc-Brian Chamberland said that since the theft, the utility has tightened security measures to ensure that such sensitive documents don't get lost or stolen again.