London commuters are struggling to get to work as Tube workers hold their second 24-hour strike in a month in a dispute over planned job cuts.
Most of the capital's underground lines are suspended or partly suspended because of a walkout by up to 10,000 Tube staff that began late on Sunday.
London Mayor Boris Johnson has called the stoppage a "nakedly political strike", noting it coincided with the annual conference in Birmingham of the Conservative Party.
He has urged the government to consider a law requiring a minimum 50 per cent participation in a strike ballot.
London Underground management held a day of talks with the RMT and the TSSA unions last month but no progress was made and the unions have refused to resume negotiations as long as a proposal to cut 800 jobs remains on the table.
The network said the job losses reflected the fact that many ticket offices were barely used since more and more passengers were buying tickets and passes via the internet or at self-service machines. It has said there will be no compulsory redundancies.
RMT General Secretary Bob Crow said managers should be "engaging in proper talks with the unions to resolve the issues at the heart of this dispute".
The unions plan two further 24-hour walkouts, on November 2 and November 28, if the dispute is not resolved and a ban on overtime remains in place.