Three Ireland has said it is aware of newly identified malware which hacks mobile phones, using a vulnerability in some sim cards, and is assessing any potential risk to customers.
Vodafone Ireland has briefed that it has no reason to believe its customers are affected by the threat.
The 'SimJacker' malware has been identified by Irish cyber security company Adaptive Mobile Security.
It says the programme gains access to the sim card in some phones to first get the location data of the phone.
However, the company says it does not stop there and can go on to use the phone to commit fraud and to monitor the user.
It says Simjacker exploits a vulnerability found in some SIM cards and the issue is not limited to one carrier or country.
It estimates up to one billion mobile phones could be vulnerable. There are over 9 billion mobile connections around the world.
Adaptive Mobile Security says it has informed the mobile industry body GSMA of the threat.
It has identified countries where Simjacker has been used to target devices but has no evidence of it being used in Ireland.
It says the group behind the malware is well resourced and has the backing of a state, but it cannot say yet which state.