Tube drivers were told by the RMT union’s chief not to turn up to work on Tuesday and Thursday this week.
General Secretary Eddie Dempsey gave the “instruction” to RMT members amid reports that the walkouts in a row over a voluntary four-day week are failing to gain the level of support of previous industrial action.
Talks are due to take place on Monday between the RMT and London Underground (LU) to try to reach an eleventh-hour agreement to avoid the strikes.
In a new development, which could signal a shift in position from the union, the two parties were set to meet with the conciliatory service Acas to seek a solution to the dispute.
An RMT source told The Standard: "Acas are ready to assist the parties in a dispute where our services are sought."
Earlier, in a memo to RMT members on Friday, Mr Dempsey made clear that the union was pressing ahead with the action unless a last-minute deal can be found.
He told of “fury” among RMT local representatives who met LU officials last week but failed to gain any changes to the proposed four-day week or for the union to have more power in negotiations on its implementation.
Mr Dempsey stressed that they had concluded that there was “no alternative but to continue with the planned strike action,” a position backed by the union’s National Executive Committee.
Putting pressure on Tube drivers to join the strike, he then wrote in bold: “To remind you, therefore, members are instructed NOT TO BOOK ON for any shifts that commence between:
“00:01 hours until 23:59 hours on Tuesday 2nd June 2026
“00:01 hours until 23:59 hours on Thursday 4th June 2026.”
Concluding his memo, Mr Dempsey said: “I trust this keeps you updated for now and expect that you and your colleagues will display another show of strength and solidarity during the strike action.”
The National Union of Rail, Maritime and Transport Workers (RMT) called off strikes on the Underground earlier in May and more than half of services ran during walkouts in April, with some RMT drivers turning up to work.
Underground drivers, who earn around £74,000 a year on average, are being offered a voluntary four-day week with no pay cut.
The RMT has branded the changes as a “fake four-day week”, arguing it is five days of work compressed into five.
It has also raised concerns that it will lead to fatigue among drivers and that they may not get early enough notice of shifts.
But its position has been severely undermined by the Aslef train drivers’ union accepting the deal and hailing it as offering the best working conditions on the whole of the mainline rail network.
Aslef says the reforms are the “biggest improvement in working conditions for Underground train drivers in decades”.
If the strikes go ahead this week, services are expected to run on most lines but disruption is likely.
Transport for London has warned there will be limited service before 6:30am and customers should complete their journeys by 9pm.
No service is expected on the Circle line, Piccadilly line, the Metropolitan line between Baker Street and Aldgate, and the Central line between White City and Liverpool Street.
Other services, including the Elizabeth line, tram, London Overground and DLR will run as scheduled but are expected to be busier than normal.
Services on the network could also be hit the days after the walkouts due to the knock-on effect.
Tube users are being urged to plan their journeys before they travel on strike days using London’s official travel app, TfL Go, or through the TfL website.
In a bid to resolve the dispute, Transport for London last week gave the RMT new reassurances that the four-week offer would remain voluntary and no driver would be forced to accept it.
Key benefits from the changes, according to Aslef, include an extra 35 days away from work a year, and average weekly rostered hours being cut to 34 from current average of 36.
It will also be easier to arrange roster patterns, it added, to block leave together, or take long weekends or mini-breaks, and would save money on travel and childcare costs.
For the first time, drivers would be allowed to volunteer for overtime which would be paid at time and a quarter.
