BRAZEN thieves diced with death when they hacked through a live wire to steal 80 metres of copper cable from a railway line.

The crooks' dangerous antics sparked a signal failure shortly after 11pm on Tuesday night.

They struck between Port Glasgow and Whinhill stations and made off with a mass of cable, which is often stripped back by thieves to retrieve the copper then sold for its scrap value.

Network Rail visited the scene of the crime early yesterday morning to begin crucial repairs and British Transport Police were also alerted at 5.45am.

They sent a scenes of crime officer to carry out forensics examinations and police colleagues helped scour the railway track for evidence, close to Gibshill Road in Greenock.

A kitchen knife was later discovered dumped nearby, and investigations were yesterday ongoing to establish whether the blade was used to slash the cable.

Police are currently forensically examining the cut ends as part of their investigation.

Yesterday, a spokesman for British Transport Police said: "This is an increasing national problem as copper prices go up in the world markets.

"It is very dangerous for people to be doing anything line-side. Some of these cables have very high voltages going through them so people who are tempted to steal cable are putting themselves in extreme danger as it's unlikely they will know what they're dealing with." A spokeswoman for Network Rail added: "It's highly dangerous to use a knife on a live cable and it's also an offence to trespass on the railway line.

"It is not the value of the cable itself that's the biggest problem, but it is the delay to train services, repair and man costs.

"This would cost several thousands of pounds, as by law we have to compensate train operators if the service is delayed.

"This results in massive costs to the industry." Rail bosses say passengers travelling on the line between Wemyss Bay and Glasgow were never at risk because, as soon as a fault appears, the signal fails and reverts to red.

Train drivers had to use a safe but delayed system to get trains along the track, which makes the service slower.

A ScotRail spokesman said: "We have a zero tolerance approach to railway crime and hope the perpetrators are brought to justice." Anyone with information about the cable theft should call transport police on freephone 0800 405040.