Australia's Foreign Minister Julie Bishop says she'll talk again with Nauru's president, Baron Waqa, over concerns about rule of law on the island when they meet today..
Ms Bishop and Mr Waqa are attending a meeting of Pacific Islands Forum foreign ministers in Sydney.
She says she has already raised Australia's concerns by phone and Australia wants an update on the prosecution of opposition MPs.
Five opposition MPs have been expelled from parliament for more than a year, with three of them now facing criminal charges after a protest outside Parliament in June, while another has had his passport suspended.
There has also been widespread criticism of new laws that restrict freedom of expression and assembly, as well as restrictions on internet access and social media.
Ms Bishop told the Australian Broadcasting Corporation that Australia wants to ensure openess, transparency and accountability to the international community.
"These are domestic matters but we urge there to be an adherence to the rule of law, that their justice system operates properly, that people are not denied natural justice, that they're given an opportunity to present their case, but I've had one confidential discussion with the president and I'll be having another one today."
New Zealand has also expressed concern about the situation on Nauru, and foreign minister Murray McCully was also due to meet with Mr Waqa.
His office is yet to comment.