London Underground passengers faced fresh delays today when services were disrupted on three lines because of problems including a failed train.
The train failed on the Jubilee line at Waterloo, while power supply problems hit the Northern line and the Victoria line was affected after a passenger became ill.
The Rail Maritime and Transport union said the Tube system was "lurching from crisis to crisis", with disruption virtually every day for the past few weeks.
General secretary Bob Crow blamed a combination of "mismanagement and financial cuts" as well as industrial action short of a strike by Tube staff involved in a row over job cuts.
Members of the RMT and the Transport Salaried Staffs Association have staged a series of strikes over the job losses and are due to walk out again at the end of the month unless the deadlocked row is resolved.
Tube drivers' union Aslef is also balloting its members for industrial action in a separate row over Boxing Day pay.