With labor contracts covering about 65,000 grocery employees about to expire, the unions and store chains agreed Monday to extend by two weeks negotiations on a new deal.

United Food and Commercial Workers locals and several grocery store chains will extend their current contract and negotiations through March 19, said John Arnold, spokesman for U.S. Federal Mediation and Conciliation Service.

In all, contracts covering workers at hundreds of Albertsons, Ralphs and Vons stores from San Luis Obispo and Bakersfield south to San Diego would have expired at midnight Tuesday.

Unions are pushing to reverse a concession they agreed to after a debilitating strike in 2003: a two-tier system they argue has kept most new workers from getting health care benefits.

Both the unions and the stores have been tightlipped about negotiations, but so far there has been no talk of a strike.

"We have settled hundreds of labor contracts with this union across the country and are confident we can also do it in Southern California," said Adena Tessler, spokeswoman for Ralphs, Albertsons, and Vons.

Kent Wong, director of the UCLA Center for Labor Research and Education, said the extension was not surprising.

"Both sides are very wary about a repeat of the last negotiations and would like to avoid the kind of acrimonious dispute that occurred three years ago," said Wong.

Ralphs locked out employees on Oct. 11, 2003, after Southern California grocery workers voted to strike against Vons and Pavilions. Ralphs brought in replacement workers to keep its stores running.

The strike cost store owners more than $2 billion by some estimates and resulted in the loss of many customers. It also made it difficult for many workers to make ends meet.

The union and the grocery chains agreed on a settlement that split employees into separate wage and benefit classes.

"Workers had been out long enough and had to come back," said Sharlette Villacorta, 35, a 13-year Albertsons employee in Los Angeles who recently took a leave to help the union with negotiations.

"But the two-tier system created a lot of anger for new workers, and most don't stay long," she said.

Under the agreement, veteran employees qualified for health care after four months and didn't have to pay any health premiums.

New hires have to wait 12 months or more to qualify for health coverage - longer for their dependents - and have been asked to pay premiums for health care.

A study released in January by the University of California, Berkeley, Center for Labor Research and Education found only 7 percent of Southern California grocery workers hired since the 2003-04 strike and lockout were receiving benefits as of September.