A female asylum seeker was found naked in the middle of the main road on Nauru after disappearing and failing to return to the Australian immigration detention centre, but Nauru police have denied she was assaulted.

The Iranian woman had been permitted to leave the immigration detention centre during the day, and was last seen two hours earlier arriving to take an evening bus. Friends told police she “seemed stressed”.

Guardian Australia reported on Monday that the woman was assaulted, but the Nauruan police have taken the unusual step of issuing a statement to refute the report.

“The female person refused to speak to the police domestic violence unit. She also refused a medical examination by doctors and told police she was not raped or assaulted. There is no injury to her or any sign of other physical force or trauma. Welfare officers and an interpreter were present during the interview process,” the statement said.

“There is no suggestion that anyone has assaulted this person. Police located her property and clothes nearby and these show no signs of physical force. Her belongings in her bags are intact including her phone.”

“The matter is an ongoing police investigation. Support and counselling are being provided to the person concerned.”

It is not clear what the nature of the Nauruan police inquiries are. Despite the statement from police, the Australian service providers on the island met to discuss what they believe was an assault at a meeting on Sunday morning.

It is understood the woman was taken into the care of International Health and Medical Services (IHMS).

When Guardian Australia put the circumstances of the assault allegation to the Australian immigration department on Monday, it said it was aware of an incident that occurred with an asylum seeker.

“The Nauru police force is investigating,” a spokeswoman said. “This is a matter for the government of Nauru … the department is unable to provide any more details.”