The Australian Greens have accused the Nauru police of intimidation and secrecy after they raided the offices of an aid agency.
Save the Children staff had computers and phones seized at the weekend during searches on their offices in the Australian-run regional processing centre.
The charity says it has no reason to believe its staff acted inappropriately and it is assisting local police with inquiries.
The Nauruan government has been concerned in recent months about leaks to the media.
Greens immigration spokeswoman Sarah Hanson-Young said Australian staff are just doing their jobs.
"This is secrecy gone mad and just more intimidation from the Nauru Police, whose actions are becoming more and more questionable," Ms Hanson-Young told AAP in a statement.
Save the Children has provided education, recreation and child protection services for children and adults detained at the regional processing centre on Nauru since 2013.
But it was told in August that its service contract will expire at the end of October and it will be replaced by Transfield.
The agency has long called for greater oversight of the Nauru facility after there were abuse claims.
