Motorists using the M4 motorway in Sydney's west and Anzac Parade in the city's east who illegally use mobile phones while driving will from January be identified using new high-tech camera systems.

Roads Minister Melinda Pavey announced on Sunday an Australian company had been selected to install the systems. The selection of the company, Acusensus, follows an earlier trial in October in which more than 11,000 drivers a day were detected illegally using their phone.

Cameras detected this driver using their mobile phone while driving 20km/h over the speed limit.

Motorists captured using their mobile phones while at the wheel will not, initially, be fined. But that will change provided the trial is successful.

"If at the end of the trial, the technology proves to be foolproof, the community will be made aware of its permanent use,” Mrs Pavey said.