SYDNEY (Reuters) - Australia and New Zealand, Nauru's two biggest donors, ramped up pressure on the South Pacific island nation on Friday to abide by the rule of law after the arrest of two opposition MPs who had criticised the government for corruption and rights abuses.

New Zealand, which provides US$1.2 million (S$1.6 million) a year to run Nauru's justice system, hinted it will reassess its aid. Australia, which has a A$2 billion (S$2.01 billion) asylum seeker detention centre on the tiny island, made the issue a priority in talks with Nauru President Baron Waqa in Sydney.

"I asked for assurances about the rule of law, the integrity of the judiciary system and the treatment of those detained or who have been charged, and I received those assurances,"Australian Foreign Minister Julie Bishop told reporters.

Bishop said she had not heard reports before her meeting with Waqa that the two lawmakers had been remanded in custody at a court hearing on Friday and another eight men detained.

Nauru media has reported that the group, arrested over an anti-government protest outside Nauru's parliament last month, has been denied access to lawyers.

Nauru is a speck in the Pacific about 4,500 km northeast of Australia with 10,000 citizens and has relied on foreign aid since the depletion of its rich phosphate mines in the 1980s. It has also been plagued by corruption allegations.