THE state's ICT sector has labelled the NBN rollout a shambles after figures revealed the number of Tasmanian premises passed by fibre plunged by almost 50 per cent between April and June.
Statistics show the number of homes and businesses passed by fibre had plummeted from 308 a week during the first quarter of the year to 168 a week in the second.
The rollout rate dropped in all states and territories except Victoria during the second quarter, with Tasmania's slowdown worse than the national average.
TASICT chief executive Dean Winter said the latest statistics were extremely disappointing.
``NBN Co needs to come clean about what is actually happening with the Tasmanian rollout,'' Mr Winter said.
``NBN Co should outline why progress has slowed and how they plan to fix it.''
At a Senate hearing in May, NBN Co chief operating officer Greg Adcock said the process for declaring a premises passed by fibre had changed.
He told the committee premises were only considered passed by fibre when 90 per cent of the surrounding area was covered.
But Mr Winter said the new reporting method did not excuse such a significant slowdown in rollout rates.
He said if the rollout continued at the same speed as it had during the second quarter, the project would take more than 18 years to complete.
``The sad thing is, it was supposed to be completed by the end of next year,'' he said.
``Tasmanians deserve to know why one of the most significant infrastructure projects in the state's history isn't being delivered on time or as promised.''
NBN Co yesterday declined to comment on reasons behind the 46 per cent drop in Tasmanian premises passed.
NBN Co spokeswoman Lalla Mackenzie said the fibre rollout across Tasmania would continue in stages.
She said 20,000 Tasmanian homes and residences were already connected to the NBN, with thousands more in the building, preparation and construction phases.