Myanmar security forces opened fire on Rohingya Muslims, committed rape and stood by as rival mobs attacked each other during a recent wave of sectarian violence, a rights watchdog said Wednesday.
The authorities failed to protect both Muslims and Buddhists and then "unleashed a campaign of violence and mass roundups against the Rohingya", New York-based Human Rights Watch said in a report.
The violence which erupted in June in Rakhine state between Buddhists and Rohingya has left about 80 people dead from both sides, based on official figures -- an estimate that HRW said appeared "grossly underestimated".
Hundreds of Rohingya men and boys have been rounded up and remain incommunicado in the western region of the country formerly known as Burma, it said.
Members of both Muslim and Buddhist communities committed horrific acts of violence with reports of beheadings, stabbings, shootings and widespread arson in Rakhine, also known as Arakan state, the report added.
"What is remarkable is that if the atrocities that we saw in Arakan had happened before the government reform process had started, the international reaction would have been swift and strong," said HRW Asia deputy director Phil Robertson.
"But the international community appears to be blinded by a romantic narrative of sweeping change in Burma, signing new trade deals and lifting sanctions even while the abuses continue," he told a news conference.
The report, based on dozens of witness interviews, said that the events in Rakhine "demonstrate that state-sponsored persecution and discrimination persist" despite the government's pledge to end ethnic unrest.
Police and paramilitary forces "opened fire on Rohingya with live ammunition", it added.
It quoted one Rohingya man in the Rakhine state capital Sittwe as saying that security forces watched as a Buddhist mob started torching houses.
"When the people tried to put out the fires, the paramilitary shot at us. And the group beat people with big sticks."
Another Rohingya man said: "I was just a few feet away. I was on the road. I saw them shoot at least six people -- one woman, two children, and three men. The police took their bodies away."
Decades of discrimination have left the Rohingya stateless, and they are viewed by the United Nations as one of the world's most persecuted minorities.
Myanmar's government considers the estimated 800,000 Rohingya in the country to be foreigners while many citizens see them as illegal immigrants from neighbouring Bangladesh and view them with hostility.
President Thein Sein in July told the United Nations that refugee camps or deportation was the "solution" for the Rohingya.
HRW also criticised Bangladesh for turning away "hundreds and perhaps thousands of asylum seekers" fleeing the recent deadly unrest in Myanmar.
The clashes erupted following the rape and murder of a Rakhine woman and the subsequent lynching of 10 Muslims by a crowd of angry Buddhists.
The violence, along with fighting in northern Kachin state, has cast a shadow over widely praised reforms by Thein Sein over the past year, including the release of hundreds of political prisoners and the election of opposition leader Aung San Suu Kyi to parliament.
Myanmar's government this week rejected accusations of abuse by security forces in Rakhine, after the United Nations raised fears of a crackdown on Muslims.
Foreign Minister Wunna Maung Lwin told reporters on Monday that the government had exercised "maximum restraint" in bringing an end to the violence.
Fears about the situation have spread across the Islamic world, with threats of violent reprisals against Myanmar from extremists from Pakistan to Indonesia.
