File picture: Nissan.

London - Driverless cars face a "real risk" of being hacked en masse when they are introduced in Britain and other countries in the not too distant future, an expert has warned.

The connected nature of these vehicles could make them a target for hackers, according to evidence submitted to Parliament.

Matthew Channon, of Exeter University, has written to MPs to warn of the danger of road accidents. In his evidence to Parliament on the Automated and Electric Vehicles Bill, he wrote: "A major issue that has not been introduced in the Bill is in relation to mass risk."

There are concerns the automated cars could be fooled into detecting obstacles which are not there and remotely slam on their brakes.

He said there was a "real risk" of multiple vehicles being hacked at the same time, as they are expected to communicate potential obstacles to each other. Mr Channon said: "Because they will be sharing information, if you hack one, it will be possible to hack the others also."

The motor insurance expert raised concerns terrorists could access the cars’ systems, after attacks where vehicles were used as weapons. However, he said the scenario was not inevitable and has been impressed by the industry’s response so far.

He also said driverless vehicles could save many lives as they reduce the risk of driver error.

Cyber-security expert Hugh Boyes said: "It has been demonstrated in the US that vehicles can be hacked. The industry has moved swiftly to try and reduce that risk but it would not be prudent to say it could never happen."