Sept. 8 (UPI) -- Millions of commuters in Britain were unable to get to work or had their journeys disrupted Monday morning after the London Underground was shuttered by a strike by around 10,000 drivers, signals operators and maintenance crew.

National Union of Rail, Maritime and Transport workers walked off the job Sunday through Thursday in a dispute over pay and what they argue are excessive working hours due to staff cuts, closing the mass transit system's eight busiest lines and impacting service on five others.

The union is demanding a 32-hour work week, down from 35 hours.

Among the lines with no service were the Victoria Line, Picadilly Line, Circle Line, Waterloo & City Line, Hammersmith & City Line, District Line and Bakerloo Line.

Transport for London, the transit authority, warned travelers on X to expect "severe disruption" Sunday through Friday with "limited Tube service, ending earlier than usual" and urged people to complete their journeys by 6 p.m.