BANGKOK (Thomson Reuters Foundation) - Police on the tiny Pacific island nation of Nauru are investigating an alleged assault on a child refugee by another refugee, the government said on Thursday.

Nauru is home to Australia’s controversial refugee detention center, which hosts about 500 asylum seekers and has been widely criticized for harsh conditions and reports of systemic child abuse.

The Guardian newspaper reported on Wednesday that an Iranian refugee had caught another refugee in the act of sexually assaulting his 6-year-old daughter on Dec. 29.

The man had pulled his and the girl’s trousers down, and abused her near the cafe where her father worked, the Guardian reported, adding that the attacker had not been arrested or charged.

The Nauru police force (NPF) is investigating the alleged assault, the government said on its Twitter account.

“NPF will not discuss details of alleged child assault investigation but confirm alleged victim and alleged accused both from refugee community,” the government said on Twitter.

“Child assault allegation involves accusation against a refugee by another refugee,” it added.

Several rights groups have criticized the harsh conditions at the Nauru detention center.

The U.N. Refugee Agency (UNHCR) said in 2013 that the center was “inappropriate for the care and support of child asylum seekers”, according to a Human Rights Watch report to an Australian parliamentary committee.

Asylum seekers intercepted while trying to reach Australia on rickety boats have been sent to camps on Nauru, located about 3,000 km (1,800 miles) northeast of Australia, or on Manus island in Papua New Guinea.

According to Australian government statistics, at the end of November Nauru hosted 543 asylum seekers, including 70 children.

In early October, Nauru unexpectedly opened the gates of its detention center, allowing asylum seekers to move freely around the island, and said it would immediately process all asylum applications.