London's tube network is expected to be paralysed by a strike later this week following the collapse of talks.
Union officials rejected a revised offer from Underground managers during a meeting at the conciliation service ACAS this afternoon.
The 24-strike will begin at 6.30pm on Wednesday. Services are unlikely to return to normal until Friday morning.
The long-running dispute is over the planned launch of the new 24-hour 'Night Tube' on September 12th.