A NEW home-testing kit that detects drug use through hair samples has been branded an invasion of privacy by civil liberties and health groups.

One spokesman said the tests would ruin trust between parents and their children.

HairConfirm, produced by American biotech company Confirm BioSciences and launched in Australia this month, is marketed to those concerned their children are using drugs.

Parents who buy the $65 kit can collect a lock of their child's hair and send it to the US to be analysed for drugs including marijuana, cocaine, heroin, ecstasy, amphetamine and methamphetamine. The results, claimed to be 99.9 per cent accurate, are available online within 48 hours.

Peter Menedis - a consultant to the kit's international distributor, Instant Drug Testing - said people had a right to know if their child was using drugs. ''The parent is responsible for the child. No parent wants to see their child descend into addiction. Every parent wants to be the best parent they can be and they want to do what's best for their children.''