Hopes of averting travel chaos for millions of London Underground passengers have been dashed after the Tube's biggest union announced that a 72-hour strike is to go ahead.
The Rail Maritime and Transport (RMT) union said more than 2,300 of its members will walk out at 6pm next Monday in a row linked to the collapse of maintenance giant Metronet.
The RMT and other Tube unions are seeking guarantees that there will be no job losses, forced transfers or cuts in pensions.
Hopes of averting the strike rose on Friday night following a meeting between the unions and London's mayor Ken Livingstone.
But the RMT said that Metronet and its administrator have failed to give it the "unequivocal" guarantees on jobs, transfers and pensions it is seeking.
A union spokesman said the strike will have a cumulative effect on services which he predicted would lead to the Tube network "grinding to a halt".
Bob Crow, general secretary of the RMT, said a letter the union had received from Metronet and the administrator fell "way short" of the guarantees workers deserved.
"What we sought was firm, unequivocal guarantees but, frankly, our members are being asked to stake their jobs and their pensions on a pig in a poke. The only assurances we have received about jobs and transfers cover only the period of administration, and that is simply not good enough.
"It is strange that the administrator can determine all sorts of things about the future of the public-private partnership (PPP) contracts, apparently including who the next fat-cat privateer might be, but is not in a position to give ongoing guarantees on the jobs of the people who actually do the work."
The unions have also warned of a second 72-hour strike starting on September 10 if the row is not resolved.
