Upgrades to the signalling system for Britain’s railway network could be vulnerable to hackers, leading to serious crashes.

That is according to Professor David Stupples, an advisor to the government, who told the BBC that replacing the ageing signal lights with new computers, could leave the rail network exposed to cyber-attacks.

A spokesman for Network Rail told the BBC that: "We work closely with government, the security services, our partners and suppliers in the rail industry and external cybersecurity specialists to understand the threat to our systems and make sure we have the right controls in place."

The European Rail Traffic Management System is currently being tested in the UK and once it is up and running, would dictate safety information such as speeds and stopping time.

While the system is already being used in other countries, without any reported incidents, Professor Stupples believes that it could be affected by malware.

According to the professor, the system is more likely to come under attack from an inside source: "The weakness is getting malware into the system by employees. Either because they are dissatisfied or being bribed or coerced."

Professor Stupples is said to be working with Cranfield University to develop a security system which could detect when a train was acting oddly.