UPDATE 1-Vale Inco Sudbury workers OK strike mandate

* Vale Inco Sudbury workers approve strike mandate

* Could walk out if deal not reached by June 5

* Talks also continuing at Voisey's Bay (Adds details. In U.S. dollars, unless noted)

By Cameron French

TORONTO, May 25 (Reuters) - Unionized workers at Vale Inco's (VALE5.SA) Sudbury, Ontario, nickel operations have voted to strike if labor negotiations with the company fail, a union spokesman said on Monday.

"There was a mandate vote, and there was 90 percent in favor of giving permission for a strike," said Bob Gallagher, a spokesman for the United Steelworkers, which represents about 3,500 employees at operations at the Sudbury nickel and copper hub in Northern Ontario.

Workers also approved an extending the life of the current contract to June 5 from May 31, said Gallagher, adding that the two sides were in face-to-face talks on Monday.

The timing of the contract expiration could be problematic for the union as Vale has announced it will shut down the Sudbury operations for eight weeks in June and July due to weak demand for the metal.

The shutdown means the company, which took over the Sudbury operations in 2006 when it bought Canada's Inco, could feel less pressure to conclude an agreement quickly.