The federal government says it will add three extra Senate Estimates sitting days at the end of the year to allow for "additional scrutiny" after initially being criticised for cancelling a day-long hearing in October.

On Thursday, the Opposition criticised the decision to scrap a dedicated day of estimates hearings for "cross-portfolio" issues — which often cover regional and Indigenous matters — accusing Labor and the Greens of having "slammed the door on accountability".

Opposition spokesperson for Indigenous Australians, Kerrynne Liddle, said the hearings — originally scheduled for October 13 — would have allowed the Coalition to press the government on why four key Closing the Gap measures "are going backwards".

"We also would have sought an answer to why Aboriginal communities in Central Australia are not feeling safer or optimistic for their future despite the Albanese Government throwing $300 million at its Better, Safer Future for Central Australia Plan," Senator Liddle said.

In response, a government spokesperson said they had "agreed to add three extra days of Senate estimates at the end of the year, to allow for additional scrutiny".

"In this round of supplementary budget estimates, Indigenous issues will be a part of every day of estimates," the spokesperson said.

"Closing the Gap is a whole-of-government responsibility. It's the responsibility of every Secretary and Minister to improve outcomes for First Nations Australians."

Senate estimates allow senators to question ministers and senior officials on government spending and performance. After the March federal budget, the estimates process was disrupted by the election campaign. The government added an extra sitting week to make up the time, but did not initially restore a dedicated day for "cross-portfolio" issues.

The revised sitting calendar confirms supplementary budget estimates will run from 7–10 October, with a second round scheduled for 1–4 December.

On Thursday, Liberal Senator Jonno Duniam labelled the initial decision "shameful".

"It is astounding that a Labor government that holds itself up as the champion of Indigenous Australians, in partnership with the Greens — who claim the same thing — would go and scrap a full day of hearings in the Senate estimates process relating to Indigenous matters," he said.

"It's not good for democracy, it is not good for accountability, and it's certainly not good for Indigenous Australians."

Labor's Senate leader, Penny Wong, countered that the Opposition would still have opportunities to ask questions on other days, adding the Coalition "didn't oppose this change earlier in the day but now is feigning outrage".

"To the leadership of the Coalition in this chamber, for many years, I was the Senate leader in opposition," she said. "I remember it very clearly, and I consistently supported the government of the day in their parliamentary sitting pattern because that was the convention.

"It is unfortunate that the coalition wants to work with Senator [David] Pocock to change the parliamentary sitting, but that's a matter for them."