A total of 17 revellers tested positive for drugs following a pioneering police clampdown in Aberdeen city centre at the weekend.

Grampian Police became the first force in the UK to use test for mephedrone – known as M-CAT - at source.

Officers used a hi-tech scanner to test more than 600 revellers for cocaine, MDMA and mephedrone.

As a result of the action, all those caught face bans from the 22 members of licensed trade association UNIGHT. Those in possession of controlled substances could face criminal proceedings.

Five bags of what is suspected to be mephedrone were recovered as a result of the two-night operation.

Grampian Police city centre unit Sergeant David Bremner, who led the operation, said: "Although mephedrone is not yet a controlled substance, its effects are similar to other controlled stimulants like cocaine.

"The effects of mephedrone are unpredictable, especially when combined with other drugs or alcohol.

A spokesman for nightclub Tiger Tiger, which volunteered to take part in the operation, said: "It's in everyone's interests that the city centre is kept as drugs-free as possible and we'd be happy to take part in a similar operation again."

The force used a mobile drug testing machine lent by oil company BP to carry out a total of 604 tests at ten licensed premises across the city centre.

The machine was specially re-calibrated to test for mephedrone.