Human Rights Watch called Monday for Somalia's government to order a new, impartial and transparent investigation into an alleged gang-rape by African Union (AU) soldiers.
The New York-based watchdog said the response to the incident "has been marred by mismanagement, opacity, and the harassment of the female rape survivor and support service providers."
A Somali woman alleged in August she had been stopped on the streets of Mogadishu by three soldiers from the national army, blindfolded and forced into a car, before being handed over to African Union troops, where she says she was repeatedly raped.
The woman, in her late 20s with a young baby, was unconscious during the attack and says she does not know how many men raped her. She was later thrown back onto the streets.
AMISOM, the 17,700-strong United Nations-mandated AU force that supports the government in its fight against Al-Qaeda-linked Shebab insurgents, said at the time it had launched an investigation.
AMISOM soldiers are drawn from the militaries of Uganda, Burundi, Djibouti, Sierra Leone and Kenya.
But Human Rights Watch said that "three months on, the government's investigation into the case has been mismanaged and no findings have been made public."
"The Somali authorities seem to be fumbling their investigation of the alleged gang rape instead of seriously pursuing the case," said Liesl Gerntholtz, the group's women's rights director.
This "points to security officials trying to silence both those who report the pervasive problem of sexual violence and those who help rape survivors," she said.
Somali officials have promised a report on the case would be released in late November, Human Rights Watch said, but added it believed it was "unlikely to yield meaningful or credible results."
The rights group said its researchers had interviewed the Somali woman in the capital and found her allegations to be credible. It also saw the woman's hospital records, which detailed "injuries that were consistent with forcible sex and other physical abuse."
But it was also told by AMISOM that the allegations were "unfounded", and detailed the alleged harassment of the victim and people helping her.
"The Somali authorities and African Union forces aren't going to make allegations of sexual violence go away with blanket denials," Gerntholtz said.
"Troop contributing countries should immediately establish clear and transparent procedures to investigate allegations promptly and impartially, and appropriately hold those found responsible to account."
After HRW's criticism, Somalia's government responded by saying there was "no space for impunity" in the country, and noting that in recent months men found guilty of rape had been executed.
"Rape and sexual violence against women are completely unacceptable in Somali culture," the government said in a statement.
However, while saying it welcomed HRW's call, the government also said the "situation is more nuanced", arguing that state institutions are still "in their infancy" after more than two decades of civil war.