UK train drivers will strike again next month as part of a long-running dispute over pay and conditions.

Aslef members are set to walk out on various rail lines on a rolling basis in early December and also refuse overtime for the first nine days of the month, the union said in a statement.

Members “overwhelmingly” voted to spread out the industrial action, the statement said, adding that the “ramifications for the rail industry will be greater.” Aslef has held regular strikes as it demands a steeper pay rise after inflation soared last year.

The Rail Delivery Group, which represents train companies, said it has offered drivers a base salary of nearly £65,000 ($80,600) a year for a four-day week and urged Aslef “to put it to its members, give Christmas back to our passengers, and end this damaging industrial dispute.”

The RMT, another union that represents rail workers, said last week that it would not strike in the run up to Christmas, pending a vote by its members.

Read More: UK Rail Strikes May End as RMT Union Puts Deal to Member Vote

(Updates with comment from train companies in fourth paragraph.)