A controversial plan for CCTV to be used to protect children in the homes of chaotic drug-abusing parents has been proposed by one of Scotland's most eminent drugs experts.

Professor Neil McKeganey, head of the centre for Drug Misuse Research at Glasgow University, believes radical measures are required to protect the estimated 160,000 children in Scotland living with an alcoholic or drug-addicted parent.

He believes the sheer scale of the problem, which was previously estimated as being far lower, makes it impossible for social workers to guarantee children's safety.

Recent figures suggest more than 50,000 children are estimated to have a parent with a drug problem and around 80,000 to 100,000 have a parent with an alcohol problem.

Social workers and children's charities last night agreed with the need for debate and further action to protect these children but disagreed with the proposal.

Mr McKeganey is known for his extensive research and controversial views. In 2004, he suggested female drug addicts should be paid to take long-term contraception to stop them having children.

"What price should we put on our privacy?" said Mr McKeganey. "The question is whether we are prepared to say the principle of the privacy of family life is more important than that of child protection. If we accept that privacy is the most important principle then there will be many more tragic cases.

"I am aware that this will be controversial but believe the debate needs to be had. We have become used to the proliferation of CCTV cameras within public spaces. We have also become used to the idea that those cameras are an effective tool in crime prevention. What we have not considered though is their possible use in private spaces."

Recent child abuse cases have highlighted the urgent need to tackle the problem.

Last year, in the wake of an 11-year-old girl collapsing in a Glasgow primary school suffering heroin withdrawal, Jack McConnell, the then first minister, announced the children of drug addicts would be more likely to be put into care.

In another case in December 2005, two-year-old Derek Doran died in East Lothian after drinking methadone in his parents' home.

Mr McKeganey added: "The response to this suggestion will be to say that it is the unacceptable extension of big brother' and a violation of individuals human rights. But the Human Rights Act was never intended to be a get out' clause for those committing crimes or harming vulnerable children."

Michelle Miller, the Association of Directors of Social Work spokeswoman on children and families, said: "This is an enormous problem and social workers by themselves are not going to fix it. It is a much wider issue than that and we need to have a detailed debate. This proposal, however, would be completely impractical."

Anne Houston, chief executive of Children 1st, disagreed with Mr McKeganey's suggestion. "The money would be better spent in increasing the resources needed to identify and support children affected by drugs and alcohol misuse."

Meanwhile, an investigation has revealed that young drug addicts in Aberdeen city without dependants are low on the priority list and may have to wait up to two years for help.