Human Rights Watch says Burmese security forces have committed killings, rape, and mass arrests against Rohingya Muslims in western Burma in the aftermath of deadly sectarian violence in June.

The New York-based group said in a report Wednesday that Burmese forces failed to intervene as long simmering tensions between Buddhists and Rohingya Muslims erupted into violence.

Human Rights Watch's Deputy Asia Director Elaine Pearson says once the Burmese forces contained the clashes, they carried out a campaign of violence and mass roundups against the Rohingya.

“One of the problems that we were able to document was that there was collusion between the security forces and the ethnic Arakan, of which the Rohingya were really the victims.”

The report comes as U.N. human rights envoy Tomas Ojea Quintana visited the areas hit by the violence. A local monk told VOA's Burmese service that about 100 Buddhists staged a peaceful protest in the town of Maungdaw on Tuesday as Quintana visited Burma's Rakhine state, near the border with Bangladesh.

U Arsi Ra said the protesters held signs urging the U.N. refugee agency UNHCR not to discriminate between Buddhists and Muslims when providing aid to tens of thousands people who fled their homes due to the riots.

“Arriving by air, Quintana met with local officials at a Maungdaw administrative office. Then, he went to see temporary refugee shelters including a high school and a monastery. Quintana leaves for Buthidaung (another border town with Bangladesh) later today. (In Maungdaw,) he is facing a protest by Buddhists who accuse the United Nations of favoring Muslims.”

Some Rakhine Buddhists perceive the UNHCR as having a pro-Muslim bias because the U.N. agency recruited most of its Rakhine personnel from Muslim communities.

The government, which has a long history of violence against ethnic minorities, has denied that security forces have committed abuses against the Rohingya, saying they exercised “maximum restraint” in dealing with the conflict.

In its report Wednesday, Human Rights Watch said the international community was guilty of being “blinded by a romantic narrative of sweeping change” in Burma, which has enacted a series of polical and economic reforms in recent months.

Burma's government refuses to recognize the country's estimated 800,000 Rohingyas as an ethnic group and many Burmese consider them to be illegal immigrants from Bangladesh.