The ACT will lead the nation with the largest of three trial launches for the National Disability Insurance Scheme, after Chief Minister Katy Gallagher agreed to join with the federal government in sharing the costs of the ground-breaking plan.

Liberal premiers from Australia's big states, however, refused to sign up to the scheme during yesterday's Council of Australian Governments meeting in Canberra and would not agree to carry the share of the load demanded by Prime Minister Julia Gillard.

Instead, NSW Premier Barry O'Farrell and Victorian Premier Ted Baillieu kept other state and territory leaders waiting for more than two hours while they held side discussions with the Prime Minister.

But the impasse was not broken, leading to a feisty media conference at the end of the day with Liberal premiers at odds with Ms Gillard.

Western Australia and Queensland also failed to agree with the Commonwealth over the scheme.

Ministers and officials from NSW and Victoria will hold further talks in Canberra today.

Ms Gallagher said it had been clear during the meeting that those could still negotiate their way into the scheme.

The Prime Minister said she was not pleased that a national agreement had not been reached, but she was sure the scheme could still succeed.

''I am very disappointed that we have not been able today to strike an agreement with either NSW or Victoria or indeed Western Australia on hosting a launch site,'' Ms Gillard said.

The ACT was announced as the largest of three jurisdictions for a trial of the NDIS, along with one for adolescents with disabilities in Tasmania and one for younger children with disabilities in South Australia.

The ACT is expected to contribute between $6 million and $8 million in 2014, the first year the three-year trial begins, while the Commonwealth will contribute $10 million.

Ms Gallagher, who used to be a social worker and an advocate for people with intellectual disabilities, said not signing up to the NDIS trail had not been an option for the ACT.

''I could not let this opportunity go by,'' she said.

''Philosophically, from my point of view this is the right thing to do. This is the fair thing to do and ultimately it will give people with a disability more support than they are getting now.

''My own view is the ACT needed to be at the start of this process and not coming in half way through.'' Currently, the ACT disability services budget is about $86 million a year. Out of that, 1400 people in Canberra are accessing the highest level of disability services.

The ACT contributes 70 per cent for each high-need place, which costs on average $35,000.

Under the new deal the ACT and federal governments would support over time up to an extra 3600 high-need places and the Commonwealth would increase its share of the cost to 40 per cent.

Ms Gallagher noted there was a risk that the ACT could experience a further influx of families from interstate accessing disability services.

She envisaged the trial would help many post-school people in Canberra who were left without support once they reached year 12.

Ms Gallagher said this would be one target group for assistance under the trial.

''There is no automatic entitlement to service once a young person leaves school. So it means many of them stay in school beyond the age of 18 and when they do leave it often means their mum has to leave work to be their full-time carer,'' she said. The national deal would have cost NSW an extra $70 million and Victoria $40 million.

The federal government put $1 billion on the table.

Mr O'Farrell and Mr Baillieu said they remained committed to the scheme, but were not happy with the funding arrangements.

Queensland Premier Campbell Newman said his state's budget would not allow him to divert more funds into disability services.

WA Premier Colin Barnett, whose trial site bid was rejected, said: ''Today, in my judgement, was an opportunity squandered.

''With due respect to the three trials that have been set up, they are small-scale, they are in the small states.'' Mr Barnett got no joy from Ms Gillard either over his plans for a re-think of how GST revenues are distributed.