RAIL operators are advising people to avoid unnecessary travel and warned trains will be extremely busy due to reduced services.

Disruption on rail networks is continuing following yesterday’s strike action by the RMT union, which saw more than 40,000 workers take part in the walkout.

Govia Thameslink Railway (GTR), which operates Southern, Thameslink and Gatwick Express services, said that trains will operate an amended Sunday service, with trains starting later in the morning.

Customers are recommended to travel later, plan their journeys and check their trips before they travel.

Strike action is also set to disrupt those heading to London, with disruption on the Underground and bus services in the capital.

Angie Doll, chief operating officer of GTR, said: “Services for the whole period between the 18 and 21 August will also start much later in the morning than usual, so please travel later in the day if you can. 

“First trains will be extremely busy and therefore you may not be able to board. Trains on strike days will also finish as early as 4.30pm so please plan ahead if you absolutely have to travel on these days.

“We’re so disappointed that rail disruption due to strikes is affecting our passengers again. We urge the RMT to work with the industry and come to a resolution.”

Only one in five trains across the country ran, with several areas having no services operating all day due to the industrial action.

A spokesman for the Department of Transport said that workers had “opted to inflict misery and disrupt the day-to-day lives of millions instead of working with the industry to agree a deal that will bring our railways into the 21st century.”

Rail union leaders said the long-running dispute over pay, jobs and conditions would continue “for as long as it takes”.

Further strike action will take place tomorrow, with services to the east and west of Sussex set to be suspended by the latest walkout.