Drivers on a London Underground line serving Heathrow airport have launched a 24 hour strike over claims of a "comprehensive breakdown" in industrial relations.
Members of the Rail, Maritime and Transport union (RMT) and Aslef who work on the Piccadilly Line walked out at 9pm, with further action planned after Easter.
The industrial action will cripple services on the line - one of the busiest on the network - until Thursday evening.
The RMT said there has been a prolonged period of industrial problems on the line, partly linked to "serious underlying issues" with the age of the trains.
RMT general secretary Mick Cash said: "The blame for this action rests solely with the LU management who have walked away from numerous opportunities to resolve the issues at the heart of this dispute. It is time for LU on the Piccadilly Line to end the macho posturing and start talking seriously with our representatives."
London Underground operations director Pat Hansberry said: "This indefensible strike has been called to protect drivers who refused to drive Piccadilly Line trains on their shifts - without good reason - resulting in delays to our customers."
Members of the drivers' union Aslef based at one of the Piccadilly Line's depots also went on strike from 9pm over the same dispute.
ends
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