Mobile firms Vodafone and O2, BT's wireless division, gave way to pressure from the government on Friday and unveiled plans for combating the country's growing problem of mobile-phone thefts. The package of antitheft measures was quickly endorsed by the Home Office.

The joint initiative between Vodafone and O2 focuses on barring SIM (subscriber identification module) cards in all phones reported lost or stolen, and developing a computer system to block calls being made from stolen handsets, the companies said in separate statements.

"I am delighted that mmO2 [O2's full corporate name] and Vodafone have agreed to take a big step forward in protecting their customers," Home Office minister John Denham said in a statement from the Home Office.

The move comes a month after the Home Office published a report estimating that 710,000 mobile phones were stolen in the UK last year — more than double the 330,000 mobile phones that were officially reported as stolen or were the target of an unsuccessful theft.

At the time the government called on mobile operators to put provisions in place to allow accounts to be cut off when phones have been stolen and IMEI (International Mobile Equipment Identity) numbers compromised. The IMEI number is a unique 15-digit serial number on each phone.

Operators Orange, Virgin and One2One backed the government's report and said they were already offering that service. But Vodafone and BT Cellnet declined to put the technology into place, saying that their older networks did not have the ability to do so.

The joint initiative between Vodafone, O2 and retailers seeks to share records of IMEI numbers across all UK mobile phone networks. But the companies stressed that seeking to block IMEI numbers was only a limited solution to cracking down on mobile phone crime.

While barring IMEI numbers stops calls from being made on the network, it does not disable the handset from being used, O2 and Vodafone said.

One possible hardware solution was promoted last month by US custom-logic chip maker Xilinx — electronic chips that can be reconfigured over a network to shut down a stolen mobile phone.

The limitation of software solutions is also a problem with another popular mobile phone antitheft technique that has been pioneered by the Amsterdam police and endorsed by the Home Office, the so-called text message bomb. Text message bombs work by bombarding a stolen phone with enough SMS (short message service) text messages to render the phone practically unusable.