A second trade union has announced it will take strike action on the London Underground (LU) next month.

The Transport Salaried Staffs' Association (TSSA) will join the RMT union in staging two 48-hour walkouts on February 4th and 11th. It claimed that 58.8 per cent of those balloted voted in favour of the action.

This figure was questioned by LU officials, who argued that only 29 per cent of the union's total membership supported the strike. It therefore claimed that the vast majority of workers either did not take part in the vote or did not want the walkout to go ahead and has appealed to TSSA leaders to call off the industrial action.

General secretary at the union Manuel Cortes said the strike was as a result of Transport for London's plans to close all ticket offices in underground stations and remove supervisors from their posts. He added that the time had come for mayor Boris Johnson to sit around the table with them and "negotiate a sensible deal which will protect the safety and security of the travelling public as well the long term interests of our members".

The news comes as a separate strike organised by the RMT union on the Docklands Light Railway has been cancelled. The walkout was supposed to begin tomorrow and was in protest of pay and working conditions.