The age limit for buying alcohol in supermarkets and off-licences would be raised from 18 to 21 in Scotland under proposals from Holyrood ministers that intend to confront alcohol misuse among teenagers.

The move, to be announced tomorrow by Kenny MacAskill, Scotland's Justice Minister, would mean that Scotland would have a higher age qualification for off-licence purchases of alcohol than any other part of Britain and almost all of Europe. Over-18s will still be allowed to drink in pubs and clubs in Scotland.

The proposal is the key plank of the SNP administration's strategy on combating binge drinking and weekend drunkenness, which lead to vandalism, violence, chronic health problems and premature death.

Alcohol misuse costs the Scottish economy £2billion a year and one Scot is said to die every six hours from a drink-related cause.

Mr MacAskill is also likely to propose in a consultation paper the banning of three-for-two and buy-one-get-one-free deals in shops and supermarkets.

There was confusion yesterday on whether the minister would also attempt to take action on the cost of alcohol by proposing minimum pricing. This could lead to 50p per unit of alcohol being added to the cost of a drink, raising the cost of a 20-bottle pack of lager from the present £9 to £14 and a bottle of wine from £3 to £5.

SNP ministers appear confident that a system of minimum pricing is within their power since it would not impinge on the duty applied to alcohol or on the VAT element - powers that are reserved to Westminster.

However, other political parties have pointed out that when a proposal for a plastic bag levy was examined officals in the Scottish Executive concluded that it was not within Holyrood's powers, although there was room for imposing it through local authorities.

The Scottish Retail Consortium (SRC), which represents supermarkets and smaller “corner-shop” retailers, said that the Scottish government would be sending out a mixed message on alcohol if it allowed people aged 18 to 21 to buy alcohol in pubs and clubs but not at an off-licence or supermarket. Fiona Moriarty, of the SRC, said that the measure risked “demonising and mystifying alcohol” for young people.

Some experts believe that ministers should concentate on enforcing the present law and ensuring stringent penalties against more shops that are found selling alcohol to under-18s.

Paul Waterson, chief executive of the Scottish Licensed Trade Association, claimed that cheap alcohol in supermarkets was making the drink problem worse. “Over the last couple of years the supermarkets have totally failed to respond to the obviously irresponsible promotions that they have within their stores,” he said.

Momentum for changing the law has come from pilot schemes in Armadale, West Lothian, and in Larbert and Stenhousemuir, Falkirk, which experimented with a ban on the off-licence sale of alcohol to under-21s and reported a sharp fall in the level of assaults, vandalism and general complaints about young people.

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