BUS drivers have been warned to be on their guard after two teenage joy-riders stole a minibus.

Police are examining CCTV footage to try to track down the thieves, who got into the unattended minibus parked at Preston Bus Station and drove it on a ten-minute journey to the Frenchwood area.

Now bus drivers have been warned to be particularly careful when leaving their vehicle at the bus station.

John Askwith, traffic manager for Preston Bus, said: "The driver had left his vehicle to go to the inspector's office for clarification on something.

The joy-riders must have waited until they saw the driver go he left and then got on board. We have now asked security to be extra vigilant, and warned the drivers."

After stealing the bus the culprits drove into a parked vehicle in Frenchwood, causing minor damage to the bodywork before abandoning it a short distance away in Greenwood Street. Their attempt to steal the money vault from the bus failed.

Mr Askwith said: "The thieves must have had a basic idea how to operate the bus from watching the driver. We are working closely with the police and looking at the CCTV to try and identify them."

Peter Corless, assistant director of environmental services at Preston Borough Council, said: "The responsibility of security is split. We have security guards who patrol the concourse of the bus station and CCTV cameras monitoring the area, but Preston Bus are responsible for their vehicles. We've got an adequate system and have no immediate plans to increase personnel."

Peter Bell, Preston Bus managing director, said: "This happened once before a couple of years ago. When a bus goes missing we know about it quickly. It is a legal requirement to have an emergency opening button on the buses, which makes it difficult to uphold security measures."

Mr Askwith added: "The joy-riders knew how to start the bus and use the master switch. We do turn the master switches off, but we can't take the keys out."

He added that he did not blame the minibus manufacturers Optare as the buses are not that easy to operate.

Two youths were seen running away from the buson Greenwood Street towards London Road. They are white and aged around 17. One was wearing a grey sweatshirt, the other a blue jacket. Call Crimestoppers on 0800 555 111 with information.