A 24-hour strike by thousands of London Underground workers is to go ahead from Sunday evening after hopes of a peace deal over job losses collapsed.
The Rail Maritime and Transport union (RMT) and the Transport Salaried Staffs Association (TSSA) said their members will walk out at 6.30pm on Sunday, threatening travel chaos for commuters and other passengers.
It will be the fourth 24-hour stoppage in recent weeks in a worsening row over 800 job losses in ticket offices.
Talks at the conciliation service Acas ended on Thursday night without a breakthrough and union leaders said they had effectively broken down, ending any hopes of a last minute deal.
London's mayor and Transport for London (TfL) set out a range of transport measures that will supplement Tube services to help people travel around the capital, including 100 extra buses and capacity for around 10,000 more journeys on the River Thames.
London Underground (LU) said it ran 40% of its normal services during the strike on November 3, rising to 50% for large parts of the day, carrying around half its normal passenger numbers.
RMT general secretary Bob Crow accused the company of "intransigence" after the union offered to suspend industrial action if management agreed to review the job cuts and their impact on stations.
He said there were fresh delays on the Circle and District lines this morning, adding: "The unprecedented and continuing chaos on the Tube has hit services again as the combined impact of maintenance cuts and failing infrastructure is rammed home.
"This daily crisis will only get worse unless there is an immediate halt to the cuts programme and urgent top-level talks with the unions to map a way forward from this chaos."
TfL said it "condemned" the leaderships of the TSSA and RMT, saying they had "scuppered" productive talks and walked away from an offer of a further six weeks to review its staffing plans.