In a widely-publicised speech on tackling alcohol-fuelled crime, Ms Smith said she will give police tougher powers to confiscate booze from under age drinkers.

Shadow home secretary David Davis said Ms Smith has promised new powers which already exist.

The Tories' Confiscation of Alcohol (Young Persons) Act 1997 gives police all the powers necessary to seize drink from children, he said.

"This is yet another half-baked announcement designed to grab a headline," he said.

"If the Home Secretary spent as much time enforcing the laws we have as she does on media strategy, we might finally start to tackle binge-drinking on our streets and the violence that goes with it."

Liberal Democrat home affairs spokesman Chris Huhne also attacked Ms Smith's pledge, which she announced at the weekend in a Sunday tabloid.

"This is all populist puffery since the police already have the power to crack down on youth alcohol, and just need to use those powers more when needed," he said.

A Home Office spokesman said police want new powers to act without suspicion that children will consume alcohol.

Ms Smith added that Britain has passed a "worrying tipping point" where a majority of 13-year-olds have drunk alcohol. The figure will amount to nearly 350,000 13-year-old drinkers in England and Wales alone, according to data from the Office for National Statistics.