US supermarket operator Kroger has posted a sharp drop in quarterly earnings, as it was hit by labour disputes in southern California and the West Virginia area.

The company reported net earnings of US$110.2m, or 15 cents a share, for the third quarter to 8 November, compared with $254.6m, or 33 cents a share, in the year-ago period.

Kroger said it estimated that the labour disputes affecting stores in southern California and the West Virginia area had reduced earnings by 12 cents a share.

Total sales for the third quarter rose 3.8% to $12.1bn, including stores affected by the strikes. Identical-store sales, excluding fuel, fell 0.6% on this basis, but edged up 0.4% when excluding strike-hit stores.

"We are pleased with our sales performance in the third quarter, especially in light of the current operating environment," said David B. Dillon, Kroger chief executive officer.

Regarding the labour disputes, which centre on health care costs, Dillon said it was not possible to say when the disputes would be resolved.