London - The craze for mobile phones among young consumers has caused a rise in child-on-child mugging across London, police said yesterday. "Practically every second child over the age of 13 has a mobile phone and it makes them vulnerable," Det Const Chris Denman said. Children are the victims of nearly half of all street crime in Harrow, north-west London, and between 80 and 90 per cent of the attackers are juveniles, he said. Although many parents give their children mobile phones for security, expensive models are prized loot for young thieves.