Power workers on London Underground have extended their strike to two weeks.
Members of the Rail, Maritime and Transport union and Unite began the walkout last night and planned to strike for eight days.
But union members have said the strike will now continue until July 15, which could have an impact on transport during the Tour de France when it comes to London on July 7.
Transport for London insisted there will be no “visible impact” on services during the walkout and other members of staff have been trained to take on the power workers role.
Mick Cash, acting general secretary of RMT,said: “This dispute is over an all-out attack on the power control grade that would hit pensions, length of service and working conditions and damage the futures of this key group of tube workers.
"Management's claim that they can run the system without them is both provocative and dangerous."
