School chiefs launched an investigation after two youngsters wrongly tested positive for drugs - because of their toothpaste!

A shocked Year 9 girl tested positive for the class A drug methamphetamine - or crystal meth - at Brightlingsea's Colne Community School, the Gazette can reveal.

A Year 7 boy at the school gave positive results for the class B drug amphetamine - also known as speed.

Assistant principal Mark Thomson said they immediately knew the results were wrong because of the pupils involved.

He said it was a trying ordeal for the girl, adding: "It was hanging over her head, which is really horrible.

"Her father was adamant his daughter had never touched drugs or illegal substances."

The girl had to wait for further tests to clear her name.

"It was rotten that the girl had to wait, but I assured her we'd sort it out. I sat her down and explained what had happened," said Mr Thomson.

"Her parents took her to a GP for a urine test which, of course, was negative - she was totally clear."

The school automatically launched a probe into what happened.

It emerged that using a leading brand of toothpaste could cause false positive drug results.

Random drugs tests at the school were immediately suspended.

Swab samples are now sent to the US for analysis and then double-checked in a lab, rather than being examined in school.

The school said no other pupils have tested positive since the pilot scheme was launched a year ago. It was just the second in the country to introduce drugs tests.

The programme has now resumed.