The Assistant Minister for Social Services, Mitch Fifield, told a forum broadcast online on Wednesday that the Commonwealth has no plans to delay the rollout of the scheme, and any change to the current timeframe would require the agreement of state and territory governments.

Speculation that the Abbott government may seek to slow down the implementation of the scheme has intensified since the release last month of a review commissioned by the board of the National Disability Insurance Agency, which highlighted early problems in the rollout.

The review concluded the Gillard government's decision to launch the scheme in July 2013, one year earlier than recommended by the Productivity Commission, had compromised planning for the scheme.

It found the IT system for the scheme was not fit for purpose, there were problems with data provided by states, and there was a lack of clear guidance for staff on how the scheme operated.

Senator Fifield insisted on Wednesday there was no "secret plan" to slow the rollout, and said, with all Australian governments and oppositions behind the scheme, there was "no way" it would not be delivered nationally. But he did not rule out any change to the agreed schedule and said he would wait for advice from the board of the agency. KPMG is providing advice to the board on the rollout schedule.

"We're not looking for ways to slow down the NDIS, we're looking for ways to deliver it," Senator Fifield said. "But I'm not going to let anything stand in my way in making sure that the foundations for the NDIS are solid."

"I'm going to follow the objective evidence and advice that governments receive from the board of the agency," Senator Fifield said. "I'm going to follow that wherever it leads."

"To make sure that people get the support they need, we have to be relentless and we have to be remorseless in ensuring that we lay the very best foundations possible."

"To do otherwise would be to let Australians with disability down, and I won't do that."

The chairman of the agency's board, Bruce Bonyhady, told the forum the nation had "one chance in a lifetime" to ensure the scheme was built "optimally and sustainably."

Asked about the possibility of a delay, Mr Bonyhady said: "The word delay implies that the board might suggest that the scheme should be delivered more slowly than the pace which we think is optimal, and we would never do that," he said.

Trials of the scheme are under way in the Hunter region of NSW and the Barwon region of Victoria as well as in Tasmania and South Australia. Trials in Western Australia, the Northern Territory and the ACT start in July.

The scheme is forecast to cost $22.2 billion in 2019-20, its first year of full operation.