SEVEN cylinders of pure nitrous oxide - known as "laughing gas" - have been stolen from a York health centre, with police warning it could kill.

The cylinders were taken from the Clifton Park NHS Treatment Centre between last night and this morning. The gas is sometimes used to provide a "high" or to boost the performance of specially-modified cars, but North Yorkshire Police said the purity of the stolen nitrous oxide made it dangerous.

All the blue cylinders are either three feet or five feet long with white collar tags carrying the name of the manufacturer - BOC - and details of their contents as well as safety advice.

"Although nitrous oxide is sometimes used recreationally, in this pure form it is hazardous to health and could even prove fatal - I urge people not to take any risks," said Pc Nick Garbutt of York Safer Neighbourhood Team.

The force has asked anybody involved in enhancing the performance of modified cars and who may know who took the gas, or who is offered the cylinders for sale, to contact officers. Anybody with information should phone Pc Garbutt on 101, email nick.garbutt@northyorkshire.pnn.police.uk, or phone Crimestoppers on 0800 555111.