The Greens New South Wales has criticised the rollout of a free Wi-Fi trial on Sydney buses, highlighting privacy concerns which the party suggests the state government has not made clear.

Transport for NSW has announced the trial which offers free internet access to commuters, which will be provided by advertising giant APN Outdoor.

Transport Minister Andrew Constance says on-demand shuttles will transform daily commuting habits. Credit:Ben Rushton

CATCH features tailored sponsored content for those wishing to avoid using their own data, though the privacy concerns lie deep within the app's terms and conditions.

Upon connecting to the Wi-Fi service, APN Outdoor will track the user's location data as well as other non-specified private information, which can be shared with third parties.