Trains in parts of southern England have been severely disrupted after a fault in a radio system.

Services out of London Waterloo, one of the UK’s busiest rail stations, have been particularly delayed.

A problem with the radio network preventing communication between drivers and signallers was reported towards the end of the morning rush hour, affecting the railway’s Wessex route connecting London with the south and south-west.

The fault has now been fixed, but disruption is expected to continue in places until the end of the day. A number of services have been cancelled, or delayed by up to an hour and a half.

Train companies advised passengers to expect some disruption, allow more time for journeys and check before travelling through the day.

The most-affected operator is South Western Railway (SWR), with trains struggling to return to normal. Some routes run by Southern were also curbed or delayed, while a number of CrossCountry, Gatwick Express, Great Western Railway, London Overground and Thameslink trains were disrupted.

The National Rail website reported that the technical problem had been resolved by 11am but warned: “Some services may still be delayed by up to 90 minutes or cancelled whilst service recovers. Major disruption is expected until the end of the day.”

SWR said services across its entire network “may be cancelled, delayed by up to 90 minutes or revised” for the rest of the day, reporting major disruption on its routes as far west as Exeter.

Southern said that trains on its Hayward Heath route would be running late or ending at Gatwick until at least 1pm.

Passengers have been told that they can use their tickets on alternative routes or operators at no additional cost.

A Network Rail spokesperson said: “Due to issues with radio communications, train services in the south-west and south have been subject to some delays this morning.

“Staff have worked to resolve the fault and train services are now returning to normal. We apologise to passengers for the disruption caused to their journeys this morning.”