Union chiefs are preparing to take on Marks & Spencer after the high street giant infuriated workers by axing double time for employees who work evenings and Sundays, it was reported on Wednesday.

Although the retailer does not recognise a trade union, the Transport & General Workers Union plans to take up dozens of individual complaints with the store's internal grievance procedure, the Daily Mirror reported.

Union bosses say each complaint will have to be looked into because the cuts amount to a change in contract conditions.

Union spokesman Brian Revell told the paper: "We are determined to take action and will be pursuing individual grievances on behalf of our members. Clearly we believe M&S should recognise trade unions and bargain with us collectively.

"We have no alternative but to take up members' claims on an individual basis. M&S should accept that unions have a legitimate role in their business."

But an M&S spokeswoman said: "Staff have been happy to deal with our Business Involvement Group which is designed to act as a network to inform staff and involve them in decision-making."