All trains into and out of Portsmouth were held up by emergency engineering works after a piece of metal fell on to the electrified third rail.
The National Rail Enquiries information line has reported that all services – which include South West Trains, First Great Western and Southern lines – were subject to delays of up to an hour.
The disruption was estimated to last until at least 7.15pm.
Because of the problems South West Trains customers can use Southern services and Stagecoach Buses on routes 21, 23, 70, 71 and 700.
A Network Rail spokeswoman said that the delays had been caused by a piece of metal lying on the electrified third rail. This had been knocking the conductor rail ‘shoes’ from trains - the devices that feed electricity from the rail into the trains. Four trains – two run by South West Trains and two by Southern Railways - were affected but were able to continue their journeys, but the line had to be closed while engineers found the piece of metal and checked the track.
It was not thought to be an act of vandalism, she added, and said that in total 11 services had been affected with a total delay time of 106 minutes.
Delays are also being caused by signalling problems between Liphook and Liss which mean trains from Guildford to Havant are running up to 30 minutes late.