Tube drivers are to vote on industrial action in a row about working conditions.
The announcement has come as Conservatives on the London Assembly called for curbs on strikes on the Underground.
The union organising the ballot called that an attack on fundamental rights.
Rags Martel reports.
More top news
Sir Bernard Hogan-Howe made the comments as an independent review into the way rape allegations are investigated.
Sir Bernard Hogan-Howe described the standard of an annual fitness test that officers must complete as too low.
Dry and cloudy tonight, winds easing. Lows of 9C.