Strike action is impacting Transport for London services in southern Hertfordshire.
Around 1,100 Unite the union members are staging a walkout today (Friday, August 19) in a row over pay and pensions.
London Underground and London Overground trains are disrupted, as well as bus routes operated by the firm London United.
Sharon Graham, Unite general secretary, said: "Our members worked through the pandemic, putting themselves and their families at risk to keep London running.
"Now they are being told they must pay for Covid with cuts to their pay and pensions and threats to their jobs.
"These attacks to their livelihoods must be taken off the table and a proper pay rise put forward or the strikes will escalate."
A Unite spokesperson said staff were not given a pay rise in 2021, and that a three per cent pay increase has been offered for 2022.
Inflation in the UK hit 10.1pc in July, the highest in four decades, well above the 3pc offer.
They also claimed the UK government is demanding Transport for London "slashes" workers' pensions and completely ends its final salary pension scheme.
Mayor of London Sadiq Khan has responded to strike action: "I am extremely frustrated by the strike action today on London Underground.
"This will have a serious impact on London’s businesses and commuters, at a time when we’re working to get more passengers back on to the network and boost the capital’s economic recovery.
"TfL have done everything they can to avoid this disruption going ahead and I’ve urged the unions to call off this action and to work with TfL to lobby the government for a long-term funding deal that is fair to Londoners and our heroic transport workers.
"I encourage Londoners to listen to TfL’s latest travel advice and avoid travelling on the Underground, and only travel if essential on the rest of the network."
A spokesperson for the government's Department for Transport said transport secretary Grant Shapps, who is also the MP for Welwyn Hatfield in Hertfordshire, has previously spoken about TfL funding deals.
In June 2022, Mr Shapps said: "The government has provided TfL with close to £5bn of funding, but by repeatedly playing politics instead of fulfilling his side of the bargain, Sadiq Khan is preventing a long-term deal from being secured."
At 2.15pm, disruption was reported on all London Underground lines.
Transport for London service updates are online: https://tfl.gov.uk/tube-dlr-overground/status/
Bakerloo line - Entire line suspended (Harrow and Wealdstone to Elephant and Castle).
Central line - Part-suspended between Liverpool Street and White City (through central London) and between Hainault and Woodford (through Chigwell in Essex). Limited service on the rest of the line.
Circle line - Entire line suspended (Hammersmith to Edgware Road, through Paddington, Euston Square, King's Cross, Liverpool Street, Tower Hill and Victoria).
District line - Part-suspended. Trains only between West Ham and Upminster.
Hammersmith and City line - Entire line suspended (Hammersmith to Barking).
Jubilee line - Entire line suspended (Stanmore to Stratford).
Metropolitan line - Entire line suspended on all routes, with no trains at Chorleywood, Rickmansworth, Moor Park, Croxley or Watford in Hertfordshire.
Northern line - Part-suspended. Trains between Edgware and Golders Green and between High Barnet or Mill Hill East and East Finchley only.
Piccadilly line - Entire line suspended (Cockfosters to Heathrow Airport or Uxbridge).
Victoria line - Entire line suspended (Walthamstow Central to Brixton).
Waterloo and City line - Entire line suspended (Bank to Waterloo).
London Overground (Gospel Oak to Barking) - No strike disruption.
London Overground (Lea Valley) - Entire line suspended, with no trains between London Liverpool Street and Chingford, Enfield Town and Cheshunt in Hertfordshire.
London Overground (North, East and South London lines) - No strike disruption.
London Overground (Romford to Upminster) - No strike disruption.
London Overground (Watford) - No strike disruption.
No strikes are taking place on the Elizabeth line or DLR.
A separate strike by RMT members disrupted National Rail lines throughout the country yesterday (Thursday, August 18).
RMT members working for Network Rail and 14 train operating companies are set to walkout again tomorrow (Saturday, August 20).
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