The RMT has announced further 24-hour strikes on London Underground on 4 and 6 October, as its dispute continues with Transport for London over job security and conditions.

The union fears that 600 staff at stations are facing the loss of their jobs and is also critical of what it describes as ‘detrimental working conditions’.

It also alleges that the staff who are left will have more work to do, sometimes alone, which increases the risk of fatigue and jeopardises safety.

The effect of the walkouts is not yet clear, but the whole system could be disrupted.

The union’s general secretary Mick Lynch said: ‘Station staff have had enough of having their livelihoods threatened by job losses and attacks on their terms and conditions.

‘Station staff have a vital role to play assisting vulnerable passengers access the network safely and ensuring that the tube is a safe environment for passengers.

‘These job cuts and attacks on conditions are going to lead to more unstaffed stations, temporary closures and rising passenger anger.

‘TfL has had its budgets slashed but the savings made by these station staff cuts will be negligible and will lead to shortages that are unacceptable. We call on Mayor Sadiq Khan to meet us urgently to discuss this matter.’

Transport for London has yet to comment.

Meanwhile, the Campaign for Better Transport has launched a campaign today to save London’s one day Travelcards, which are set to be withdrawn next year in a bid to increase Transport for London revenue. The CBT said the loss of the Travelcards would increase the costs of travelling around the capital by an average of 16 per cent.

The CBT’s Norman Baker added: ‘At a time when we should be doing all we can to encourage people to use green public transport to access London’s shops and attractions, this move is going in entirely the wrong direction. Public transport works best when you can use one ticket for your whole journey, so we need more, not less, integrated ticketing.’