The number of schoolchildren stealing mobile phones from one another has risen sharply in the past three years, police figures show.
A school child is now a victim in almost two in every five muggings
Nearly 15,000 secondary school pupils in London were robbed in the 11 months to February - 5,000 more than in the same period in 2002/3.
Police say the rise is due to a surge in "schoolboy on schoolboy" robberies.
Metropolitan Police Commissioner Sir Ian Blair has made tackling the crime a top priority.
He wants the mobile phone industry to ensure stolen handsets are made worthless by barring them across all networks once they are reported as stolen.
Cut in funding
"This cannot go on, it has to stop," he said.
"The change is so significant that we have to be looking to work with education and the mobile phone industry to stop it happening."
A school child is now a victim in almost two in every five muggings and 49% are said to involve mobile phones.
Scotland Yard no longer receives £14m from the government as part of the Safer Streets crackdown on muggings.
Instead, they will work with the phone industry, school officers and its new Violent Crime Directorate.
Sir Ian said he understood parents bought phones to help keep their children safe and encouraged them to continue to do so.
"But what we have got to do is get to a situation where there is no point in stealing them - the only way to do that is with the industry," he added.