Rail services to and from the country’s busiest railway station were disrupted for a second successive day on Tuesday after a fire under a train.

South Western Railway services were cancelled or delayed after the incident between Surbiton and Weybridge.

The company said disruption to services, including those to and from London Waterloo, will continue for the rest of the day.

The company had already warned of delays because of the heat.

Services were hit on Monday because of a series of incidents including points and signal failures, trespassers and a person hit by a train.

In a message to passengers, SWR said: “With the exceptionally warm weather this week, rail temperatures are expected to reach 47 degrees in certain locations throughout our network, Network Rail have advised us that emergency speed restrictions are required between London Waterloo and New Malden on lines heading away from London Waterloo.

“These speed restrictions, which vary between 20mph and 40mph will be in operation on country-bound lines between London Waterloo and New Malden from 11:00 on the 26/06 up to and including 29/06.

“Trains may lose up to 10 minutes before reaching New Malden station and may be held at signals for longer.

“In addition to the above, there was a small fire underneath a train between Surbiton and Weybridge which is currently blocking the Woking bound line. We expect disruption until the end of the day.”

Passengers were still on the train hit by the fire over an hour and a half after the incident happened.

SWR said in a later message to its customers: “If you have an alternative route to your destination that does not use London Waterloo station, we advise you to use that service.”

Mick Cash, general secretary of the Rail, Maritime and Transport union, said: “There have been two days of chaos on South Western Railway services out of Waterloo on the hottest days of the year with RMT members left to take the rap at the sharp end. The conditions for passengers and staff alike are simply appalling.

“The situation yet again reinforces the need for adequate numbers of staff, including guards on the trains, to deal with the pressure-cooker conditions on our railways that are now becoming a matter of routine.”

SWR and Network Rail said in a joint statement: “We would like to apologise to passengers for ongoing delays to services into and out of Waterloo today, and advise them to avoid travelling through Waterloo this evening if at all possible.

“This is due to two lines being blocked after an electrical fire on the underside of a train carriage near Surbiton at 1420 this afternoon, which also caused a loss of power to the neighbouring line.

“No one was injured in the incident, and the emergency services and Network Rail engineers were on site promptly to deal with the fire, remove passengers safely from the train and repair damage to the railway. Both lines have now reopened.

“We once again apologise to passengers for the delays and ask them to check before they travel for the rest of the day as trains could be cancelled or services revised at short notice.”

SWR said there were additional delays on trains heading to Portsmouth from London and to London from Portsmouth at Woking owing to a points problem.