Tube drivers 'refused to pick up' after doors problem
Union leaders have said delays were caused to Tube passengers after some train drivers refused to pick them up over safety fears about doors.
The RMT said the action followed concerns over safety on some Piccadilly Line trains.
Transport for London (TfL) said the issues were resolved earlier and normal services had resumed.
However, it said the Piccadilly Line had been affected by a signal failure on Friday.
TfL said the delays had been downgraded to minor on Friday evening.
The RMT said the action, involving up to 25 drivers, followed an incident on Thursday night near to Piccadilly Circus where doors did not close properly.
London Underground said the train involved in Thursday's incident was taken out of service.
It said it had tested the doors on the rest of its train fleet and no failures were found.
A TfL spokesperson said: "Last night, just before 8pm, a driver on a Piccadilly Line train at Piccadilly Circus station discovered that two doors on the last carriage did not close correctly as the train started to move along the platform at slow speed.
"The safety system operated and the driver followed the correct safety procedures.
"The passengers were all safely escorted off the train, which was immediately taken out of service pending a full investigation."