Former head of National Disability Services Chris Tanti has told News Corp newspapers he was shocked at the spending extravagance.

"I certainly was surprised at some of the hotels people would stay at and the restaurants that were attended ... the use of chauffeur-driven limousines was extraordinary by some," the Daily Telegraph reported Mr Tanti as saying on Saturday.

Mr Shorten, now opposition spokesman for the NDIS, says the revelations "should at least be investigated".

"The problem with the NDIS and the people at the top is this is a system where no one is running it, it's adrift, it's a runaway train," Mr Shorten told reporters in Melbourne on Saturday.

"Today's revelations ... of senior executives in disability services dining out on the disabled is yet again another symptom of the core problem ... there is sickness at the heart of the NDIS."

He said there are hundreds of thousands of fellow Australians who live with profound and severe impairment and have a right to an ordinary life.

"The money is there to help them but it's not getting to the people that it needs to get to," he said.

Finance Minister Mathias Cormann stressed there is no government agency involved in these accusations.

"It is a private sector organisation, and it is obviously a matter for them to explain themselves as to how they are conducting their affairs," Senator Cormann told reporters in Perth.

He said the government is investing significant funding into providing better care and support to Australians with a disability and their families.

"Obviously, we want to see that money reach those people who deserve that support," he said.

Australian Associated Press