More than 55,000 people in Scotland are misusing illegal drugs like heroin and methadone - almost twice as many as previously estimated - according to figures published yesterday.

In the first nationwide study of hard drug use in Scotland, the findings confirm Glasgow as the drugs capital of the country, with an estimated 13,788 addicts, or 3.8% of all inhabitants aged between 15 and 54.

Dundee, with an estimated 2700 users (3.5%), and Aberdeen, with 3645 (3%), have the second and third highest rates of people using opiates and benzodiazepines, followed by Inverclyde (1280 users, 2.8%), Renfrewshire (2441, 2.5%), and Edinburgh (5872, 2.2%).

Among young people, however, the league is topped by Inverclyde, which has an estimated 521 users between the age of 15 and 24, or 5.1% of the total number of addicts; and Aberdeen, with 1356 young users (4.7%).

These figures compare with 3229 (3.7%) in Glasgow, and 1546 (2.4%) in Edinburgh.

As well as confirming the long-standing and relatively well-studied drug problems existing in Scotland's main urban areas, the researchers also found an alarming increase in the use of heroin and methadone in rural parts of the country.

The study, carried out by the Centre for Drug Misuse Research at Glasgow University and the Scottish Centre for Infection and Environmental Health, also warns of an impending problem for health services in dealing with the predicted rise in the number of people testing positive for the hepatitis C virus.

Dr Gordon Hay, the senior researcher on the project, said the findings revealed that problematic drug misuse was occurring in all parts of Scotland, with an average 2% of the population using opiates, temazepam or methadone.

In particular, the study highlighted that:

l Unless there is a marked increase in rural-based drug services, the problem there will increase significantly in coming months and years.

l There is a demonstrable link between problematic drug misuse and deprivation and that efforts to tackle drug misuse should be integrated with initiatives to deal with social exclusion.

l Drug injecting remains a very significant problem in Scotland and there is a clear need to continue to encourage those who use illegal drugs to avoid injecting.

l Scotland is facing a major problem in relation to the hepatitis C virus, which will have major implications both for the health services and the drug users and their families.

Iain Gray, the deputy justice minister, said a better understanding of the scale of the country's drug problem was vital in ensuring that funds were effectively targeted: ''The report gives us a much clearer picture of the drug problem in Scotland's communities, and what we have to do to improve things.''

He said the Scottish Executive, which commissioned the research, had invested an extra (pounds) 34m this year to increase by more than 50% the number of drug misusers receiving treatment.

Previously it had been estimated that there were 30,000 problematic drug misusers - defined as those likely to access addiction and treatment services, and excluding people using cannabis, ecstasy or cocaine - in Scotland.

But the report's authors claimed this figure was a ''best guess'' and had not been arrived at scientifically.

Mr Gray said: ''This report is the first attempt to get an accurate picture of problematic drug misuse in Scotland.

''This problem did not appear overnight and is a sad reflection of the failed policies of the past.

''There is also a clear commitment within the Scottish drug strategy to base drug misuse policy and service provision on hard facts.''

The minister said the research would be used to make decisions of future funding allocations to tackle the problem and that similar studies would be commissioned every three years to monitor trends.

Alistair Ramsay, director of Scotland Against Drugs, welcomed the study, saying it would enable services to be planned, delivered, and assessed more effectively.

''At last we have got some properly collected statistical information,'' he said. ''In the past, most of the information we used has been based on either anecdotal evidence or the opinions of experts, which is just not good enough.

''This research gives us a base line from which to plan the provision of programmes and treatment services and, assuming it will be carried out on a regular basis, give us a way to assess the success or otherwise of the various services being offered.''

Meanwhile, the government yesterday announced plans to tighten drugs legislation, which would require Scottish courts to consider confiscation of criminal assets.

George Foulkes, the minister for state for Scotland, told the House of Commons committee that is scrutinising the proceeds of crime bill about concerns that the discretionary confiscation arrangements proposed for Scotland were insufficiently robust and out of line with the mandatory scheme envisaged for the rest of the UK.

''This change is no criticism of the Scottish judiciary, who have always pursued confiscation of criminal assets, but underlines the government's determination to send a message to criminals in every corner of the UK that they will not benefit from their ill-gotten gains.''

''We are determined that there will be no hiding place for drug dealers and others guilty of serious crime.''

The move follows meetings between Mr Foulkes, Scottish Parliament deputy first minister Jim Wallace, lord advocate Colin Boyd and Iain Gray, deputy minister for justice.