THE builder of the $37 billion high-speed National Broadband Network (NBN) says it is working feverishly to meet its most recent construction targets.

In its updated corporate plan released in August, NBN Co projected its fibre cable rollout would pass 286,000 existing premises by June 2013, with 44,000 lots connected.

It's already about one-fifth of the way there, with figures for September showing 52,014 premises have now been passed, with 6358 active fibre customers.

"We are still working feverishly," NBN Co chief Mike Quigley told AAP this week.

"I won't pretend that any of those milestones are easy to hit, but we are doing everything we think necessary to get there, yes we are."

The NBN, which is Australia's biggest public infrastructure project to date, is also on course to meet another key performance measure.

It expects the number of premises where construction of the network has begun or been completed to hit 758,000 by December 30. The final data will be released in mid-January.

Opposition communication spokesman Malcolm Turnbull has criticised the benchmark, saying the term "premises where construction has commenced or been completed" is complete nonsense and designed to mislead people about the progress of the NBN.

But Mr Quigley said the measure addresses questions about where the network has begun and when it's coming to homes.

"We had an obligation to tell people which places were going to be started," he said.

"This is not a trivial milestone."

NBN Co will release its updated three-year plan, another year of rollout data and a new corporate plan by the end of May next year.

Mr Quigley also rejected claims the current take-up rate of fibre-to-the-premise (FTTP) NBN connections - one in four - was low considering the timeframe since the NBN connections were activated.

Only 13 per cent of households had dial-up internet connections four years after its introduction, while just 28 per cent had ADSL services after six years, he said.

"As we disconnect the copper, it's really going to take off after that," Mr Quigley said.

"Take-up rates are phenomenally high compared to the introduction of the two previous technologies."

The fixed copper lines will be switched off 18 months after NBN Co has declared an area ready for service, with customers migrating across to the fibre network.

Under the government's $37.4 billion project, NBN Co will deliver wholesale high-speed broadband services by connecting fibre optic cable to 93 per cent of homes, schools and businesses by June 2021.

The remaining seven per cent will be connected by fixed wireless and satellite technologies by 2015.

Originally published as NBN says it's on track for 2013