The competition watchdog has raised concerns that Telstra may benefit against its rivals from the information it gains while helping to build parts of the NBN.

Telstra today announced its latest deal with the NBN, worth around $1.6 billion, for planning and construction services on part of the NBN network.

The deal relates to areas currently covered by Telstra's existing Hybrid Fibre-Coaxial (HFC) network footprint in Sydney, Melbourne, Brisbane, the Gold Coast, Adelaide and Perth.

Telstra will be in charge of planning the construction works and performing building work within its exchanges, while construction work in the field will mainly be undertaken by the NBN's existing partners.

However, the Australian Competition and Consumer Commission has raised concerns with the deal, warning that it might give Telstra an unfair advantage over its competitors in selling NBN services.

"We have raised several concerns with Telstra and NBN Co, including that Telstra may receive a competitive advantage if it has access to better information than other service providers or if it is able to use infrastructure built for the NBN network before that infrastructure becomes available to other retail service providers," said the regulator's chairman Rod Sims in a statement.

Mr Sims acknowledged that Telstra's participation in construction, and use of its HFC network, could speed up the NBN rollout, so the regulator is assessing proposals made by Telstra and NBN Co to address its competition concerns.

NBN Co has responded to the ACCC's statement by clarifying that its agreement with Telstra is not subject to regulatory approval.

It also said it was mindful of these "perceived issues" when structuring its deal with Telstra and sought to address remaining concerns through additional measures, including reporting back to the ACCC on a regular basis.