A Tube strike is likely to cause disruption to commuter trains in Hertfordshire, Cambridgeshire, Bedfordshire and Norfolk.
Great Northern passengers are likely to face longer journey times and diversions when London Underground staff strike on Tuesday, March 1 and Thursday, March 3.
Trains are expected to run, but five of Great Northern's London stations will be closed and services could be busier.
There will be no trains between Finsbury Park and Moorgate.
This means that trains will not call at Drayton Park, Highbury and Islington, Essex Road, Old Street and Moorgate.
This is because some of these stations are owned and run by London Underground.
Trains to Moorgate will be diverted into London King's Cross.
Some trains will only run north of Finsbury Park.
A company statement reads: "Southern, Great Northern and Thameslink trains around London are also likely to be much busier than usual and journeys may take much longer generally.
"Passengers should check before they travel online at National Rail Enquiries."
There is no planned strike for Great Northern staff.
But some London Underground staff plan to strike because they say that they have not been given enough assurances that jobs, pensions and working conditions will be safe in a transport funding crisis.
A statement by the RMT trade union reads: "Our members will be taking strike action next week because a financial crisis at London Underground has been deliberately engineered by the government to drive a cuts agenda.
"This would savage jobs, services, safety and threaten their working conditions and pensions.
"These are the very same transport staff praised as heroes for carrying London through Covid for nearly two years, often at serious personal risk, who now have no option but to strike to defend their livelihoods."
Andy Lord, Transport for London's chief operating officer, said: "No proposals have been tabled on pensions or terms and conditions, and nobody has or will lose their jobs as a result of the proposals we have set out."
Do you have a breaking news story in Hertfordshire or Cambridgeshire? Email: hertslivenews@archant.co.uk or cambslivenews@archant.co.uk
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