A woman has been arrested in Somalia's capital after she alleged in a video interview posted online that she had been raped at gunpoint by colleagues.

The journalist who interviewed the 19-year-old has also been detained in Mogadishu, but the two men accused of rape have not been arrested.

It has been reported that the arrests came after those accused of rape complained about defamation.

The UN has called for a "proper investigation" into the case.

Earlier this year, another alleged rape victim and the reporter she had spoken to were sentenced to a year in prison for "offending state institutions".

They were later released on appeal.

'Dignity destroyed'

Somalia's UN-backed government said it could not get involved in the current judicial process and justice must take its course.

The alleged victim is herself a journalist who works for the Kasmo Voice of Women radio station in Mogadishu.

Fatuma Abdulkadir Hassan told a journalist at the privately owned Shabelle Media Network that she had been raped at gunpoint by colleagues who worked at the state-owned radio station.

One of the journalists contacted her by phone and asked if she could help him without making it clear how - and a car was sent to her house to collect her, she said.

She alleges it dropped her off at a house where she found the two journalists.

"One of the men threatened me with a pistol, and took me to the bedroom by force... both of them raped me several times, destroying my pride and dignity," the AFP news agency quotes Ms Hassan as saying in the interview, which was videoed and posted online by Shabelle and has since been picked up by several Somali news websites.

The men kept her at the house the whole night, only releasing her the following morning, she said.

"I am appealing to the government to take legal action against the rapists - they might have done the same to other poor girls," she added.

Police arrested Ms Hassan, the Shabelle journalist Mohamed Bashir Hashi who conducted the interview, and the manager of Shabelle.

The manager has since been released on bail; the other two remain in custody.

Somali journalists' union leader said they had been arrested because the woman's colleagues had complained to the police, accusing her of defamation, AFP reports.

Government spokesman Abdirahman Omar Osman denied that the arrest of the journalist was an attack on the media.

"Journalists perform a critical role and we want them to be able to work without fear or favour," he said.

"A free press is at the heart of every democracy and is guaranteed under our new constitution."

Shabelle's radio station was forced off air last month when the authorities took possession of its headquarters, saying the building belonged to the government.

But the company's online operations have not been affected.

Human rights groups say rape and sexual abuse is a growing problem in Somalia where more than two decades of conflict have seen clan-based warlords, rival politicians and Islamist militants battle for control of the country.