New Zealand's parliament has unanimously passed a motion expressing concern about the political situation in Nauru.

It follows the recent suspension of opposition MPs and a recent anti-government protest on the island-nation.

The motion was moved by the Green Party's global affairs spokesperson Kennedy Graham.

Sorry, this audio has expired NZ concerned about rule of law on Nauru

New Zealand's foreign minister Murray McCully indicated earlier this week that his patience was running out over the goings-on in Nauru.

In an interview with Radio New Zealand, he said he would raise his concerns with Nauru's president Baron Waqa at a Pacific Island Forum meeting soon.

"To say we are deeply concerned about the reports that have been coming out, would be an understatement," Mr McCully said.

"The situation in Nauru has obviously been boiling for some time and this last series of events, particularly around the restrictions being placed on members of the parliament is something I think will attract a more significant international attention."

Legal academics in New Zealand have also called for their government to stop funding the justice sector in Nauru in an open letter.

The New Zealand Law Society's convenor of its rule of law sub-committee, Austin Forbes QC, said he believed what was happening in Nauru was worrying.

"We regard it as quite serious ... there are a number of international bodies that have a similar view about developments and the deteriorating state of the rule of law and democracy in Nauru," Mr Forbes told Radio Australia's Pacific Beat program.

"[New Zealand is] the primary provider of aid for the country's ministry of justice and also for its border control.

"So there are specific areas in which New Zealand has at least some leverage if they thought that taking that step was the only alternative."

Claudia Geiringer, professor of law at the Victoria University of Wellington and the director of the New Zealand Centre for Public Law, said she signed the letter because she felt "something needed to be done".

"You have the dismantling of an independent judiciary, or at least some significant pressure on the independence of the judiciary," she said.

"You have the removal, in effect, of the opposition so there is no parliament scrutiny of the government.

"And you have very significant inroads on freedom of expression so there is no public scrutiny of the government, and when you put all of that together you've got a government that really is able to do whatever it likes."

The ABC has contacted a spokesman for Nauru's government for a response.