Mobile phone users have been put on alert after it was revealed that sim cards can now be hacked, possibly leading to fraud and soaring premium rate bills.

Mobile operators are now taking steps to try and patch the security gaps before customers are hit.

The security flaw is due to ageing sim card security technology, which has struggled to keep up with hi-tech smartphones. The flaw was discovered by German programmer Karsten Nohl.

"Give me any phone number and there is some chance I will, a few minutes later, be able to remotely control this SIM card and even make a copy of it," Mr Nohl told reporters yesterday.

Mr Nohl said that a quarter of all sim cards he tested could be hacked.

Irish Independent