Commuters brace for chaos as strike shuts London Underground

Commuters at Earls Court underground station, awaiting the arrival of a train, attempt to complete their journey on Wednesday evening, in London, Britain, July 8, 2015. [Photo/Agencies]

Union officials accused management of failing to negotiate seriously, but London Mayor Boris Johnson branded the strike "totally unnecessary, cynically timed and politically motivated.''

Prime Minister David Cameron's spokeswoman, Helen Bower, described the strike as "unacceptable and unjustified''.

"It's going to hit families, workers and businesses across the capital,'' she said.