Thousands of workers at 18 bus companies in London are to stage a one-day strike in a row over pay, threatening travel chaos in the capital.

Up to 27,000 bus drivers and other workers, all members of Unite union, will walk out on January 13 as part of a long-running campaign for a single agreement covering their pay, terms and conditions.

The union said that in contrast to Tube drivers, there is no collective pay deal for bus drivers, with wages negotiated on a company by company basis.

There are more than 80 different pay rates covering drivers doing the same job, leading to differences in hourly rates of over £3, said Unite.

Wayne King, the union’s London regional officer, said: “Passengers pay one fare to travel on London’s iconic red buses, yet there are over 80 different pay rates covering bus workers, many doing the same job or driving the same route but for different rates of pay.

“Strike action is not a step our members take lightly, but bus workers who keep London moving 24 hours a day, seven days a week, have had enough of pay inequality and unfair pay disparities.

“The blame for the disruption that strike action will cause sits squarely with London’s bus companies. They have repeatedly ignored our offers for collective talks and need to get their heads out of the sand and start negotiating meaningfully about ending pay inequality on London’s buses.”

Mike Weston, Transport for London’s Director of Buses, said: “Bus drivers are employed by private companies and their pay and conditions are a matter for those companies and the union to discuss. The current system provides the best value for money for the residents and visitors to London and allows the individual bus companies to determine the best terms and conditions for their individual operating requirements.

“We are very disappointed that Unite have decided to disrupt Londoners by announcing strike action, particularly given the low turnout for the ballot, and would urge them to think again.”

The bus companies involved in the dispute are Arriva North, Arriva South, Selkent, London General, Metroline, Metroline West, Metrobus, CT Plus, London United, Abellio South, Abellio West, London Sovereign, Stagecoach, Blue Triangle, Northumberland Park, Tower Transit, Docklands and London Central.