Workers at Loblaw Companies Inc. have voted in favour of strike action that could affect the Ontario branches of Canada's largest grocery chain just before the Thanksgiving weekend.

The workers, members of the United Food and Commercial Workers, have voted 95 per cent in favour of giving their union a strike mandate, the UFCW said.

Loblaw three-month trading.

The 27,000 Loblaw workers are in a legal strike position on Friday, but no strike deadline has been set.

Loblaw is trying to win concessions as a way of dealing with competition from other chains and especially from non-union Wal-Mart, which is planning to accelerate its grocery-selling operations in Ontario.

The union said talks are continuing. But in a statement, the UFCW said the negotiations so far have been "difficult and complicated."

The talks affect Loblaws, Zehrs and Real Canadian Superstore locations across Ontario.

Loblaw shares finished down 16 cents at $47.22. The stock fell as far as $46.50 earlier in the day to reach a new 52-week low.

The chain has faced a number of hurdles recently, including the departure of its president, and earnings that have been in decline while it dealt with a new supply chain system that has taken time to implement.