Transport for NSW has ruled out smartphone apps that allow motorists who are not taxi or hire-car drivers to receive money for offering lifts.

In response to a new low cost ''ride-sharing'' service offered by Uber, which allows non-taxi drivers to offer a taxi-like service, the state's transport department said on Wednesday all drivers needed to be accredited under the Passenger Transport Act.

This would rule out Uber's ride-sharing service as it currently operates, though not apps that make it easier for taxi customers to book an authorised cab or hire car.

''The law is clear and has not changed: if a NSW driver is taking paying members of the public as passengers, the driver and the vehicle must operate in accordance with the Passenger Transport Act,'' Transport for NSW said in a statement on Wednesday morning.