SNP ministers refused to back down last night on the issue of banning off-sales to under-21s, crashing to inevitable defeat by 72 votes to 47 and vowed to press ahead with the controversial plans.

SNP ministers refused to back down last night on the issue of banning off-sales to under-21s, crashing to inevitable defeat by 72 votes to 47 and vowed to press ahead with the controversial plans.

The move - part of a package of measures put forward by ministers to tackle Scotland's drink problem - has already been criticised by student leaders, retailers and drinks manufacturers.

A spokesman for First Minister Alex Salmond said: "We believe the proposal to raise the age of purchase in off-licences and supermarkets is a very strong proposal.

"It is based on a number of very successful pilots and ministers believe therefore it was important to look at the success of these pilots and to consult on rolling out the very considerable benefits across the rest of Scotland."

The spokesman said a Bill to introduce those measures was likely to be outlined before the end of this year. He said: "Ultimately it will be for parliament to decide."

The day began with a student demonstration outside Holyrood with protesters bearing placards highlighting the anomalies of the SNP proposals.

Joining the Army, getting a job and paying taxes, starting a family, or voting in the country's future - all were contrasted with the notion that young people could not buy a drink.

Last night Gurjit Singh, president, NUS Scotland, said: "NUS Scotland and Cardas (Coalition against raising the drinking age in Scotland) have fought hard against this proposal. From the beginning we have said that this plan would be discriminatory and unworkable. Today, opposition parties have overwhelmingly agreed with us.

After the vote Justice Secretary Kenny MacAskill said: "Alcohol misuse is costing Scotland more than £2.25bn a year, this is causing problems in our health service and criminal justice system and undermining our economy. This government will not stand by and do nothing."

Conservatives, Labour, Liberal Democrats, Greens, the parliament's only independent, student bodies and others, all criticised the notion of an under-21 off-sales ban.

Tory deputy leader Murdo Fraser said: "The SNP are creating a ludicrous situation whereby students cannot buy a bottle of wine or a few cans of beer to enjoy in the hall of residence or flat.

"They are creating an even more ludicrous situation whereby a soldier returning from a tour of duty in Iraq or Afghanistan at the age of 20 cannot buy a bottle of champagne from the off-licence to celebrate with his wife on his return."

Mr MacAskill said: "The party that sought to be tough on law and order now seems to accept the disorder that flows from a free-for-all on alcohol retailing. They've moved on from David Cameron's hug a hoodie' to Murdo Fraser's free bottle of Buckie' or David McLetchie's give them all a carry-out' idea."

He highlighted pilot bans in areas such as Stenhousemuir, adding: "It's easy to dismiss the age 21 discussion out of hand, but where it's been tried locally the results have been positive. The police and the communities have both been very grateful for the successful outcomes that there have been."

Liberal Democrat Ross Finnie said: "The next generation has to been seen as part of the solution, not part of the problem."

Green MSP Patrick Harvie hit out at the "Puritanism" which pervaded Holyrood debates, adding: "The reality is that our drinking, moderate drinking, is society's recreational drug of choice and people do it because its fun."