Police on the Pacific island nation of Nauru, which is under scrutiny over conditions and reports of child abuse at an Australian immigration detention centre it hosts, on Thursday raided the offices of aid group Save the Children, the group said.

It is the second raid in recent days on the Nauru offices of the group, which has not had its contract at the centre renewed after sparring with the Australian government over conditions at the camp.

Asylum seekers are a hot political issue in Australia and successive governments have vowed to stop them reaching the mainland on rickety boats, sending those intercepted to camps on Manus island in Papua New Guinea and Nauru.

The raids are likely to add to pressure on Australian Prime Minister Malcolm Turnbull to address the policy, after reports of systemic child abuse and sexual assault and criticism by the United Nations and human rights groups.

Save the Children spokeswoman Lily Partland said the raid was believed to be aimed at locating the confidential source of a recent critical report on the centre published by Guardian Australia. Laptop computers were seized by police, she said.

The organisation has conducted a full internal audit and found no evidence that it was the source of the leaked information, which discussed efforts to limit media access to the camps.

Nauru has made it virtually impossible for journalists to visit by imposing a non-refundable A$8,000 ($5,760) visa application fee which few media outlets are prepared to pay.

"We continue to fully co-operate with Nauru police on this matter, and our priority remains working to mitigate the harmful impacts of offshore immigration detention, to the extent that the circumstances allow," Partland said.

The raids are the latest in a series of embarrassing incidents involving the Nauru centre that have helped turn up pressure on Turnbull, who said last month he was concerned about conditions in the camps.

The incidents overshadowed the launch of Canberra's bid to join the U.N. Human Rights Council on Monday, with the treatment of a pregnant Somali asylum seeker brought to Australia from Nauru for an abortion likened to CIA-style rendition.

A spokesman for the Nauru government did not immediately respond to a request for comment. ($1 = A$1.4)