Union leaders have called for a boycott of Safeway stores throughout North America in support of 70,000 grocery workers involved in a labour dispute in Southern California with Safeway, Albertsons and Kroger.

Over the next few weeks, the United Food and Commercial Workers union, which represents the striking and locked out workers, said it would ask consumers not to shop at Safeway stores in the US and Canada, reported Reuters.

Talks between the union and the three grocery chains are set to resume on Friday.

However, Safeway spokesman Brian Dowling said the threatened boycott was nothing new.

"It's an old tactic and it won't impact what's going on in Southern California. The irony is we're going to the bargaining table on Friday and they're calling for a boycott," he was quoted by Reuters as saying.

The dispute began on 11 October, as workers objected to the companies' plans to make employees contribute more to health care costs.