Thousands of commuters from Brighton, Hove and Portslade were dealt a double blow by thieves this morning (Tuesday 6 September).
Cable thefts near Littlehampton and London Bridge stations added cancellations, diversions and delays to their journey to work.
And the disruption has continued into the evening rush hour with London Bridge still affected by the problem on an unpleasantly wet and windy day.
The independent charity Crimestoppers has offered a £1,000 reward for information leading to the arrest and conviction of the thieves.
Train operator Southern said that the cable theft in London had been causing delays of up to 75 minutes this morning and was still causing delays of up to 45 minutes.
A spokesman said: “This continues to cause problems for passengers who live on the south coast but work in London.
“We don’t have a time for the return to normal running.”
A British Transport Police (BTP) spokesman said that about 30ft of cable was stolen from the Bermondsey area, on the approach to London Bridge.
The spokesman said: “The act of stealing, or attempting to steal, cable is extremely dangerous.
“Anyone who has any information about the incident or who saw any suspicious activity in the area is asked to come forward.
“What thieves don’t realise is that they are working on live cable, carrying up to 25,000 volts, which can cause extensive burns.
“By attempting to steal it they are seriously putting their lives at risk.
“BTP have a dedicated team of officers who work proactively with Network Rail and train operating companies to counteract the delays and discomfort passengers suffer when thieves target the essential resources that keep the trains running.
“Metal theft causes significant disruption to rail services and that means real consequences for real people – missed business meetings, family celebrations and important appointments for instance.
“And that’s not to mention the huge financial costs to the rail industry and the dangers to the thieves themselves.”
Separately thieves stole more than 160ft of cable from between Littlehampton and Ford, close to the A259 bridge.
Southern said: “Just after midnight signalling problems became apparent at Littlehampton.
“After investigation it became clear that signalling cable had been stolen.
“As a result Southern services were diverted to run via Barnham and Bognor Regis, causing delays of 25 minutes or so for most of the morning peak.
“The repair was made at approximately 9am and services are now running normally.”
The BTP spokesman added: “In July two brothers, Jason and John Tusting, were imprisoned for over eight years for cable theft-related offences on the rail network.
“A man they were with died while they ransacked a railway substation in Bromley.”
Robin Gisby, managing director of network operations for Network Rail, said: “Yet again, mindless thieves have caused delays and disruption for thousands of commuters across the south east.
“The costs incurred as a result of this crime are likely to run into the hundreds of thousands of pounds, which is money we would otherwise spend on improving and maintaining our rail network.
“Cable theft is a huge issue and one which the rail industry is committed to tackling– but we can’t do it alone.
“We need to see tougher sentences for cable thieves in the courts and the police must be given the powers they need to shut down the scrap dealers who are profiting from the travelling public’s misery.”
Anyone with information can call the BTP on 0800 405040 or the independent charity Crimestoppers anonymously on 0800 555111.