After recent reports suggesting the possibility of hacking the computer system of certain cars remotely with a Bluetooth phone, Finnish security firm F-Secure tried to replicate the feat. It had no success.

F-Secure tested a Toyota Prius in its underground facility but, despite repeated attempts, achieved only a minor Bluetooth hack.

"We managed to find one minor issue with the system, in which a corrupted phone name would freeze the onboard display. But otherwise the Prius Bluetooth system was far more stable than our test phones and PCs," said Jarno Niemela, a researcher at F-Secure's laboratory.

"We had to reboot our test systems several times as the Bluetooth systems died on us, while the Toyota Prius just kept going. It was definitely one of the more interesting virus tests we've done for quite a while."

The team believed it had had some success when the car's doors locked, every warning light lit up and the onboard computer registered a serious failure. However, it turned out to be nothing to do with Bluetooth, but simply that the car's battery was low.

The rumour of viruses affecting cars started in January when security company Kaspersky was asked to investigate an apparently infected car. No details of actual infections have ever been published.