The 15-year-old schoolgirl was found dead in an elevator at a south London apartment building this week, the 16th teenager slain in Britain's capital this year.

Most, like Dawit, were stabbed to death - and most of their killers were other young people.

The deaths have sparked fears of a knife crime 'epidemic' among Britain's young, and spurred the government to announce tougher penalties for teens caught carrying a blade.

'Carrying a knife is completely unacceptable,' Prime Minister Gordon Brown said on Thursday, announcing an end to Britain's system of issuing warnings to teens under the age of 18 caught with knives.

Now, anyone 16 or over who carries a knife with a blade longer than 3 inches (7.6cm) will be prosecuted. Those convicted face up to four years in prison.

'Young people need to understand that carrying knives doesn't protect you; it does the opposite - it increases the danger for all of us, destroys young lives and ruins families,' Mr Brown said.

For a major city, London has a low murder rate. Police say there were 159 homicides from April 2007 to the same month this year. But the number of under-age victims has risen. According to police figures, 27 teens were killed in 2007, and 16 so far this year. Eleven of the 16 were stabbed to death.

Many young people say pressure to carry - and use - knives is growing.

'It's increasing. It's stupid things like 'you have spoken to my girlfriend, I'll slash you up',' said Ms Monique Morrison, 21, one of a group of young people who met Mr Brown to discuss the problem.

The regularity of stabbings over the past few months has alarmed Londoners. The victims include 18-year-old Rob Knox, who had a small part in the upcoming Harry Potter film. He was stabbed to death while trying to break up a brawl outside a south London bar on May 24.

Two weeks earlier, it was Jimmy Mizen, a popular 16-year-old, who was stabbed with a piece of glass.

Dawit, an Eritrean immigrant, had complained to police about an earlier assault. A 21-year-old student has been charged with her killing.

'It's not even a shock any more' to hear about stabbings, said 16-year-old Vogue Huell, a student from Bromley, the south London district where Knox was killed.

'It's the whole gang culture, I think. As soon as one person gets stabbed, someone goes after another person.'

London's new mayor, Boris Johnson, has also vowed to crack down on knife crime. His proposals include metal-detecting arches at train and subway stations.

The city police recently began an aggressive new programme to search anyone for knives without having to justify their suspicions.

Some experts, however, say the measures are little more than political posturing.

Mr Enver Solomon, deputy director of the Centre for Crime and Justice Studies at King's College London, believes most teens who carry knives do so because they have been the victims of crime and don't feel safe.

'Unless you address that feeling of insecurity, you are not going to have a big impact on the number of kids carrying knives.'

ASSOCIATED PRESS