Hopes have been raised that next week’s strikes by London Underground drivers could yet be averted, after sources said the RMT union had put out feelers for talks.

The RMT members, almost half of London’s Tube drivers, are due to strike for two 24-hour periods from midday on Tuesday and Thursday, closing some lines entirely and bringing widespread travel disruption to the capital until the weekend.

The action follows a similar wave of strikes in April, with more planned for June in the dispute over a planned four-day week working pattern.

No talks have yet taken place and with neither Transport for London nor the union apparently willing to alter course, further strikes had appeared inevitable. TfL has warned passengers that many services will not operate next week.

However, a source close to the dispute said that union representatives had now reached out to seek a deal, giving TfL a “window of opportunity” to prevent further strikes.

They said that tube drivers were prepared for a long strike campaign of disruption, adding: “It is clear TfL needs to move from its uncompromising position and make some new proposals that do not impose new working conditions that tube drivers will not accept. An opportunity exists for the employer to do the right thing by Londoners and make a reasonable offer to the union.”

With the strike still expected to take place, TfL has urged customers to plan ahead expect significant disruption, with early closures of services on Tuesday and Thursday and late starts on Wednesday and Friday.

No trains at all will run on the Circle line, Piccadilly line, and in Zone 1 on the Metropolitan line and the Central line.

However, TfL stressed that Londoners and visitors would still be able to travel around the city, with other rail lines and transport modes running, and even some Tube trains during the two 24-hour strike periods.

The Elizabeth line, London Overground and DLR will run as normal, as well as buses, although increased demand and traffic is likely to slow some services.

Data from the last strikes in April showed that people continued to travel with patronage across the entire TfL network down only 13-14% overall on most strike days, and approaching normal levels on the Friday.

The bike hire firm Lime reported about 20% more trips than average on strike days, while rival Forest said rush hour hires were up between 35% and 50%.

Tap-ins to the tube were down between 42% and 48% from Tuesday to Thursday but only 31% on Friday, when travel on TfL services was down 6% overall. Friday now sees far less commuting, but the figures suggest Londoners returned to the tube in the evening for leisure, despite some ongoing disruption.

TfL said it was not too late for the RMT to withdraw its planned strike action, and said the objections the union has raised would be resolved with further, more detailed work. The Aslef union, which represents a slight majority of London Underground drivers, has backed the TfL proposals for a four-day week.

Claire Mann, TfL’s chief operating officer, said: “It is disappointing that the RMT is planning this strike action despite our best efforts to resolve this dispute. We have been clear that our proposals for a four-day week are designed to improve work-life balance and are entirely voluntary.

“A significant number of drivers have indicated that they want us to progress plans for the pilot of this new working pattern on the Bakerloo line, and it would deliver benefits both for our colleagues and our customers. We urge the RMT to work with us so we can resolve this dispute. In the meantime, we are asking customers to check before they travel and allow plenty of extra time for their journeys.”

The RMT union declined to comment.