One in four parents say they do not know enough about recreational drugs to talk to their children about them, a survey suggests.

However, half of parents have spoken to their children about drugs, the survey of 500 parents for national drugs information service Frank shows.

But it also suggested that many may be missing key signs their loved ones may be taking drugs like cannabis or acid.

A third of parents over 45 felt schools should teach children about drugs.

The campaign devised a questionnaire to test parents' knowledge of drugs and their use to discover how well-informed they were.

While some parents were clued up on street names for drugs, many - some 24% - did not know what 'skunk' (a particularly strong type of cannabis) referred to.

And one in five did not recognise that the term Charlie meant cocaine.

Mothers appeared to score more highly on knowledge and concern than fathers - who appeared to take a more laid back approach.

Nine out of 10 mothers believed they could spot the warning signs of drugs use compared to 82% of fathers.

More mothers saw withdrawal from family or friends and money disappearing without evidence of purchases as clues that drugs could be being used.

Confidence

Frank spokesman James Robinson-Morley said: "The good news is that the majority of parents seem to have a sound basic knowledge of the dangers of drugs.

"Parents tell us they would like to feel more confident about their knowledge of drugs and drug-taking, and how to handle having the 'drugs conversation' with their child."

Vivienne Evans from Adfam, a charity committed to supporting families facing drug or alcohol problems, said families could play a vital role in educating children.

"But lack of information and fear of "saying the wrong thing" can prevent these discussions from taking place.

"Parents need accurate, up-to-date information about drugs and guidance and how to cope when drug us becomes a problem."