Lidia Thorpe welcomes sovereignty assurances over voice but remains undecided

Greens senator Lidia Thorpe has welcomed a government assurance that the Indigenous voice to parliament will not cede First Nations sovereignty while also emphasising additional caveats on her position.

Almost half of all young people in detention in Australia are Aboriginal and Torres Strait Islander children, even though the overall number of children going to jail has fallen in the past five years, research shows.

The co-chair of the Indigenous voice co-design group, Tom Calma, said state and territory governments were primarily responsible for incarcerations rates, not the federal government.

McCarthy rejected claims the federal government had not sought to reduce Indigenous incarceration rates, citing the work of her senate colleague Pat Dodson, who sat on the deaths in custody commission.

Some Greens members, such as senator Sarah Hanson-Young, have strongly backed the voice and say they will support the referendum. It opens the possibility that the Greens will be split on the final vote.

The Greens are still in negotiations with the Labor government over the voice, but expect to come to a final party room decision in early February.