MOGADISHU (Reuters) - Somalia's prime minister on Sunday said the authorities will do more to protect rape victims after foreign donors and human rights groups criticised the arrests of a woman allegedly gang-raped by soldiers and a journalist who interviewed her.

The trial of an unidentified 27-year-old woman, her husband, and the freelance journalist has sparked international concerns over sexual violence and press freedom in the country.

The trio face prison terms of several years on charges including insulting a government body, making false accusations, and seeking to profit from the allegations.

Human rights groups say the trial is politically motivated, designed to cover up rampant sexual abuse of women by Somali security forces, while the U.N. and the United States have voiced concerns about the treatment of rape victims.

Recently-appointed Prime Minister Abdi Farah Shirdon Saaid promised to reform Somali armed forces and the judiciary once the trial has concluded, acknowledging "deep-seated problems" with both institutions.

"We recognize the concerns of our international partners and we are only too aware of the enormous challenges our nation faces," Saaid said in a statement.

For two decades the Horn of Africa state has been plagued by civil war, anarchy and Islamist insurgencies. However, September's peaceful elections, the first since military dictator Mohamed Siad Barre was overthrown by warlords in 1991, have been heralded as the dawn of a new era for Somalia.

The U.N.'s Special Representative of the Secretary-General on Sexual Violence in Conflict, Zainab Hawa Bangura, on Saturday called for the Somali government to deal with the country's rape problems, saying the U.N. had evidence around 1,700 women were raped between January and November last year in camps for internally displaced people around Mogadishu.

Saaid, a former businessman who is married to an influential Somali peace activist, said the government has launched public campaigns designed to bring down instances of rape. However, he concedes more can be done.

"I have since urged the government in the strongest terms to be much more responsive on this question, to take proactive measures, prosecute any such crimes and provide all appropriate care to the victims," he said.

Journalism organizations and human rights groups say arresting a journalist and putting him on trial for interviewing a rape victim is an attack on media freedoms and free speech.

Somalia is one of the world's most dangerous places for journalists, with killings of reporters reaching an all-time high in 2012 when 18 media workers were killed, according to the National Union of Somali Journalists.

But Saaid stressed the government's support for press freedom, saying "journalists perform a critical role and we want them to be able to work without fear or favor".

Saaid said the government will soon form a new and independent task force on human rights which will investigate attacks against women and violence against journalists.

(Reporting by Andi Sheikh and Drazen Jorgic; Editing by Jon Hemming)