Last minute engineering work will impact south London and Surrey commuters until mid afternoon today South West Trains (SWT) has said.
There are fewer trains to and from Wimbledon this morning after emergency engineering works disrupted the service.
SWT said earlier this morning disruption was due to last until midday, but it has now been revised to 3.35pm.
A statement from SWT said services running across the whole SWT network may be delayed by up to 20 minutes or revised at short notice.
The statement said: "Our engineers will be taking a line blockage of one of the four lines (stop access to trains so they can work) between 1pm and 2.30pm so they can work on the defect to raise the speed restriction on the line to 20mph."
Disruption affected commuters across south London and Surrey.
The problem is due to a defect on one of the train tracks running through Wimbledon on the line running away from London Waterloo.
Trains are being allowed to run at five miles per hour over the faulty line, which means there is a queue of trains and delays at Wimbledon station today, the statement said. The statement said: “In order to minimise delays and congestion, it has been necessary to make some alterations to our services this morning.
“We will be reducing the number of services running to and from London Waterloo.”
It said it will introduce the following amendments to the service: Trains which run between Waterloo and Shepperton will run non-stop from Wimbledon to Kingston.
Trains between London Waterloo and Dorking will not be running in either direction - Customers will need to use alternative trains to Epsom and change there for Southern services, or join Southern services from London Victoria or Clapham Junction.
Trains between London Waterloo and Chessington South will not be running in either direction - Customers will need to use London buses.
Trains between London Waterloo and Hampton Court will not be running in either direction - Customers will need to use London buses.
Trains between London Waterloo and Guildford via Cobham will make an additional stop at Berrylands.
The statement said: “While we work to introduce these service changes customer may see trains that are still running on the routes listed above and further ad hoc alterations are also possible. Please plan your journey at www.nationalrail.co.uk.”
Tickets will be accepted on other reasonable routes.
South West Trains apologised for the disruption.