The New Zealand Law Society Te Kāhui Ture o Aotearoa is concerned at the Kiribati Government's treatment of its judiciary.
The government last week appointed its Attorney General Tetiro Semilota as the acting Chief Justice.
This comes because of the suspension of New Zealand's William Hastings as Chief Justice after he founded in favour of another expatriate judge, Australian David Lambourne.
The government had tried to deport Judge Lambourne after taking exception to his rulings.
He is the husband of the Opposition Leader, Tessie Lambourne.
The New Zealand Law Society is one of a number of international legal bodies to speak out about the threat posed to the judiciary and rule of law in Kiribati by the actions of the government.
It said the appointment of the attorney general to such a post challenges the independence of the judiciary and the constitutional separation of powers that is fundamental to a functioning democracy.
The society said as a high ranking member of the government executive this move makes the government 'judge in its own cause' in litigation involving the government.
It said it is vital for the people of Kiribati that their judges apply the law to both citizens and the state independently, without fear of recrimination or challenges to their impartiality
New Zealand's Ministry of Foreign Affairs and Trade has also spoken out.
A spokesperson said judicial independence is crucial for any healthy democracy. Aotearoa New Zealand continues to encourage the Government of Kiribati to ensure its decisions do not negatively impact the functioning of the judiciary.
The spokesperson said the ministry doesn't yet know whether the acting chief justice has formally resigned her position as attorney general.