The federal government has promised nobody will miss out on the national disability insurance scheme despite concerns some children will be locked out.

The scheme has also pledged support for people with mental illness, as long as their disability inhibits their daily activity.

South Australia, which is trialling the scheme for children under 13, says its rollout is six months behind and some kids are set to miss out.

State disability minister Tony Piccolo will use a disability reform council meeting on Friday to call for the early access to a special fund set up to finance the scheme.

He argues a massive backlog in trials is causing frustration and financial pain for families and service providers, and wants funds to cover extra children.

Source: SBS.com.au