Los Angeles ? Four days of secret, informal negotiations between Southern California grocery workers who have been on strike for three months and their employers ended Sunday without success, a union spokeswoman said.

Representatives from seven local unions and from the grocery chains Ralphs, Vons and Albertsons met at a secret location without a federal mediator in hopes of producing a settlement, said Ellen Anreder, a spokeswoman for the United Food and Commercial Workers.

The talks were intensive and “completely off the record” until they broke down Sunday, she said.

About 70,000 grocery clerks from Kroger Co.’s Ralphs, Safeway Inc.’s Vons and Albertsons Inc. walked out Oct. 11 over contract differences, particularly the cost and scope of health care benefits for current employees and future hires.

Anreder said formal negotiations will resume later this month, although she didn’t have a specific date.