Thousands of British railway workers will stage further strikes over the next two months in a long-running dispute over pay, the RMT union said on Tuesday, signalling travel disruption before and after the Christmas holiday period.

Over 40,000 rail workers will go on strike on Dec. 13-14, 16-17, Jan. 3-4 and 6-7, the RMT said in a statement after talks with train operators ended without a resolution.

“This latest round of strikes will show how important our members are to the running of this country and will send a clear message that we want a good deal on job security, pay and conditions,” RMT general secretary Mick Lynch said.

Rail workers in Britain have staged several strikes this year, including the country’s biggest rail strike in decades during the summer, over demands for better pay during a cost-of-living crisis.

The RMT had earlier suspended strikes planned for early November to allow for negotiations to resolve the dispute, but said on Tuesday that industry bosses had failed to offer any new pay deals.

The Rail Delivery Group, which represents train operators, said in response the two sides had made “real progress” in recent talks that had resulted in the “outline of a credible deal” for the first time in months.

“We are asking the RMT to stay at the negotiating table, work with us towards a fair deal and end a dispute that is harming passengers, the industry, and their members,” the Rail Delivery Group said, warning of travel disruption around Christmas.