Strikers closed 13 of Marks & Spencer's 18 French stores this week, hitting the retailer's summer sale, which began on Tuesday, Retail Week reported.

The strike started last Friday when staff and management failed to reach an agreement about pay and working hours during the sale.

An M&S representative told Retail Week she had no idea how quickly the dispute could be resolved.

The strike is the latest fight to break out between French staff and M&S management as they wrangle over the UK-based retail giant's planned closure of continental stores.