Under-18s make up half of all robbery suspects

Of 35,400 arrests, 17,100 - almost 49 per cent - were of under-18s.

The sharp rise in youths involved in robberies comes amid growing concerns that police are losing control of street crime after several years of success.

Many offences are thought to be muggings where teenagers steal mobile phones and iPods.

Two years ago just 43 per cent of robbery suspects were minors: 15,100 out of 34,700 arrests.

Shadow Home Secretary David Davis said: "It is alarming to see arrests for such serious offences increasing so much amongst the young.

"This is more evidence that Labour have failed to be tough on crime and its causes, betraying a whole generation in the process."

The stark illustration of the extent of youth crime came as overall arrests for suspects of all ages rose.

Across all crime categories, arrests were up 6 per cent to 1,429,000. That means there was an arrest made approximately every 20 seconds.

Of all those arrests a quarter of suspects were children, with 349,000 of those taken into custody being under 18.

Arrests for violence leapt by 13 per cent last year to almost half a million - a huge increase of 75 per cent over the past six years.

They included 87,000 juveniles arrested on suspicion of assaults - one in five of all those arrested for violence.

Fears are also mounting of a growing trend in serious knife and gun crime involving juveniles following a spate of fatal attacks on teenagers in Britain's cities.

Last year robberies recorded by police rose to a three-year high of 101,370, and the rise was blamed on the end of special Home Office funding provided as part of a high-profile crackdown on street crime.

While police made 449,000 arrests for assaults last year that is still only a fraction of the estimated 2.4 million violent incidents last year, meaning that in four out of five attacks police never even catch a suspect.

Last year the British Crime Survey - based on interviews with thousands of households and hailed by ministers as the most reliable measure of crime trends - showed a 5 per cent increase in violent crime.

Crime and the race divide

Black people are six times more likely than whites to go to prison and seven times more likely to be stopped and searched by police, official figures showed today.

Ministry of Justice data showed the stop-and-search gap last year was even wider than the previous year, when black people were six times more likely to be stopped on the street or while driving.

Asians were about twice as likely to be stopped and searched as whites, and there was an 84 per cent rise in searches of Asian people specifically under antiterrorism powers.

While black people make up around 2.8 per cent of the population, the figures also showed they accounted for 10 per cent of the 2,327 murder victims recorded by police over the past three years.

Around 28 per cent of black murder victims were shot, compared with 10 per cent of Asian victims and 5 per cent of white victims.