LOS ANGELES - Union workers at Arizona grocery stores operated by Kroger Co and Safeway Inc set a Friday evening strike deadline if a contract agreement is not reached, a union spokesman said on Wednesday.

Some 25,000 workers at Fry's and Safeway supermarkets around the state could walk off the job on Friday at 6 p.m. (0100 GMT Saturday) if salary and benefit terms are not reached, union spokesman Bob Grossfeld said.

Safeway and Fry's signed a mutual lockout agreement in the event the union calls a strike at only one of the companies, according to an article in the Arizona Republic.

The agreement calls for the nonstriking company to lock out its union workers if a strike is called against the other.

The combined chains have nearly 250 stores around the state. Company representatives were not immediately available for comment.

Sales at U.S. grocery stores have been slumping with the recession. A protracted strike could hurt results from this year's Thanksgiving holiday on Nov. 26.

This year's Thanksgiving sales are expected to rise 3 percent from 2008, reaching $29.9 billion, according to industry research firm IBISWorld. (Reporting by Lisa Baertlein; Editing by Derek Caney)