The director of the Federal Mediation and Conciliation Service, Peter Hurtgen, who is mediating negotiations aimed at ending the Southern California grocery workers labour dispute, has said that the issues between representatives of the United Food and Commercial Workers union and the supermarket chains "remain difficult".

Hurtgen recessed the recent round of negotiations and said he will maintain frequent contact with the parties during the recess period and will request that negotiations resume "when it is appropriate".

"We've reached a point where I believe a recess will help the process. I will ask the parties to return to the table when I determine that it might be fruitful to resume face-to-face discussions," Hurtgen said.

The dispute between the UFCW and US grocery retail chains Albertsons, Kroger's Ralphs and Safeway's Vons centres on attempts by the retailers to make staff contribute to rising health care costs.