AS many as one third of shops in Southampton may be selling alcohol to under-age children, new research suggests.

The city council carried out 120 test purchases on licensed premises over a 12-month period.

Of these 39, or a third, resulted in a sale to underage volunteers.

The figures, which cover the 12 months to November 2005, were obtained by the Liberal Democrats.

They came as it was revealed the average amount of alcohol drunk by 11 to 13-year-olds every week across the country has almost doubled from 5.5 units in 1996 to 10.1 units in 2006 - an increase of 4.6 units (84 per cent).

The increase in alcohol consumption among 11 to 13 year olds is particularly marked among girls, where it has more than doubled.

In 1996, the average 11 to 13 year old girl drank 4.0 units of alcohol a week, whereas in 2006 she drank 8.4 units a week - an increase of 4.4 units (110 per cent).

The average amount of alcohol drunk by all children aged between 11 and 15 in the previous week is now, at 11.4 units, the highest since records began in 1990.

The figures were published by the NHS Information Centre for Health and Social Care.

They come as the Daily Echo's Keep Kids Sober campaign is encouraging adults and parents - as the main source of alcohol for younger children - to take a more active and responsible role in teaching kids about the consequences of alcohol and to think before supplying them with drink.

Sandra Gidley, Liberal Democrat MP for Romsey, said: "Ministers have been repeatedly warned about the dangerous side-effects of heavy drinking, but the Government has allowed public health budgets to be raided to cover deficits elsewhere.

"A fresh look at tackling the growing problem of excessive drinking is long overdue. A good start would be cracking down on those shops that sell alcohol to underage children.

"Problem drinking often starts at a young age, so it essential we make it harder for underage teenagers to get hold of alcohol. As well as causing chaos in A&Es on Friday nights and anti-social behaviour, irresponsible drinking results in serious long-term health problems."