Staff are unhappy about pay and conditions

The GMB union said 250 members at the depot in Wigan would walk out on five days in December, starting next Thursday, and one day in January.

A JJB spokeswoman said management had made an improved offer to staff.

A GMB spokesman said the union would have a consultative vote of workers at two mass meetings.

Workers had also voted to ban overtime as a result of the dispute, which involves changes to working hours and pay.

The strike action could hurt JJB Sports' Christmas plans as the warehouse supplies all of its 430 shops across the UK.