Over 90,000 Rohingya refugees have been displaced due to violence between Muslim Rohingya and Rakhine Buddhists in Burma, and many are seeking help in Bangladesh. Video from June 2012. guardian.co.uk

At least 13 women, including teenagers, have been subjected to prolonged rape by Burmese security forces in a remote village in the western state of Arakan. Human rights groups have warned that the incident threatens to trigger further violence in a region where several waves of ethno-religious rioting since June last year have killed more than 1,000 people.

The women all belong to the Muslim Rohingya minority, which has borne the brunt of fighting between Muslim and Buddhist communities. One victim, an 18-year-old girl who cannot be named for security reasons, described how a group of uniformed soldiers from Burma's border security unit, known locally as NaSaKa, entered her house in northern Maungdaw township shortly after midnight on 20 February.

"They took us separately to different places and tortured and raped us," she said, referring also to her mother and younger sister, 15. The ordeal lasted until dawn, she said. "They came in and out of the house at least 15 times. They also beat my mother with a gun and dragged her outside to the road and beat her to the ground."

According to the victim, 13 people in the village were assaulted. Chris Lewa, head of the Arakan Project, which has monitoring teams in Maungdaw township, said she had separately confirmed that at least 11 people were raped that night.

The incident comes eight months after the rape of a 26-year-old Buddhist woman by three Rohingya men triggered fierce rioting across Arakan state , and a state of emergency remains in place. Arakanese and Rohingya communities have clashed a number of times. Animosity toward the Muslim group is widespread among Arakanese, many of whom consider them to be illegal immigrants from Bangladesh.

"Sexual violence by Nasaka against Rohingya women has been documented for many years," says Matthew Smith, a researcher with Human Rights Watch, adding that prosecutions are rare for rapes committed by security forces.

Khin Ohmar, founder of the Women's League of Burma, said that such ordeals terrorise the community. "I've heard of cases where rape survivors are kicked out of their village because the village head is so scared of retribution if they complain to the Burma army."

Rohingya Muslim women and boys cross the Naf river into Bangladesh to escape sectarian violence in Arakan state, Burma, in June 2012. Photograph: Munir Uz Zaman/AFP/Getty Images

She said that incidents like these happen "every time the army moves into remote areas", and that punishment is normally just transferral to another area "where rape continues but with different women". She thinks that the 20 February incident probably had its roots in "ethno-centric chauvinism and hatred" of the Rohingya.

Following the attacks, villagers fled into nearby forests and across the border into Bangladesh, said Lewa. The victim told the Guardian that she and the other women had received treatment at a local clinic. The extent of their injuries is unclear, although one 19-year-old woman is believed to be in a critical condition.

The protracted violence in Arakan state has left deep scars for communities on both sides. The UN estimates the number of people displaced since June to be around 120,000, the majority Rohingya.

There are fears however that the violence, which initially pitted Rohingya against Arakanese, is increasingly being demarcated along religious lines. Rioting broke out in Rangoon this week after a row over what local Buddhists claimed was the illegal construction of a mosque. The Norway-based Democratic Voice of Burma news organisation also reported last week that the government had placed a ban on all Muslims leaving the Arakanese town of Thandwe, although no official statement has been made.

Buddhist and Muslim communities in Arakan state have now been segregated. In the state capital of Sittwe, all but one Muslim district was razed and emptied last year; the last remaining quarter, Aung Mingalar, whose population swelled from 5,000 to 8,000 residents after fighting broke out, is now guarded by soldiers.

Following a visit to several camps for the displaced this month, UN envoy Tomas Quintana spoke of his concern about aid distribution and freedom of movement. Despite government assurances that displaced Rohingya could eventually return to their homes, Quintana said that stakeholders in Arakan state believed "the current settlements will become permanent".

The medical charity Médecins sans Frontières (MSF) has warned that its staff have received threats from local Arakanese when attempting to get aid to the Rohingya. "It's just awful intimidation and threats of violence from a small but vocal group, through phone calls and on social media," said Peter Paul de Groote, Head of Mission for MSF in Burma.

"Formal permission for access is not the main problem. A big obstacle for MSF is not having enough staff – doctors and other essential personnel are scared to work in Rakhine [Arakan] state." He added that with monsoon season approaching, "we can expect a real humanitarian problem".