London mayor Boris Johnson has teamed up with his counterparts in New York and San Francisco to crack down on the epidemic of smartphone thefts.
Some 10,000 handsets are stolen in the capital each month and it is thought that many are being sold on to other countries where they are worth more.
Mr Johnson has written to phone manufacturers asking them to "come up with a technical solution that can squash the illegal smartphone market". He is due to hold a meeting with them on the issue in September, his office said.
London is now a member of the Secure Our Smartphones (SOS) initiative which was launched in the US to help police, politicians and public safety activists to work more closely.