Yangon: Myanmar is committing crimes against humanity in its campaign against Muslim insurgents in Rakhine state, Human Rights Watch said on Tuesday, calling for the U.N. Security Council to impose sanctions and an arms embargo.
A government spokesman rejected the accusation, saying there was no evidence, adding that the government was committed to protecting rights.
Myanmar has also rejected U.N. accusations that its forces are engaged in ethnic cleansing against Rohingya Muslims in response to coordinated attacks by Rohingya insurgents on the security forces on Aug. 25.
It says its forces are fighting terrorists responsible for attacking the police and the army, killing civilians and torching villages.
The military campaign has sent nearly 440,000 refugees fleeing to Bangladesh, most of them Rohingya. They have accused the security forces and Buddhist vigilantes of trying to drive Rohingya out of Buddhist-majority Myanmar.
"The Burmese military is brutally expelling the Rohingya from northern Rakhine State," said James Ross, legal and policy director at New York-based Human Rights Watch.
"The massacres of villagers and mass arson driving people from their homes are all crimes against humanity."
The International Criminal Court defines crimes against humanity as acts including murder, torture, rape and deportation "when committed as part of a widespread or systematic attack directed against any civilian population, with knowledge of the attack".
Human Rights Watch said its research, supported by satellite imagery, had found crimes of deportation and forced population transfers, murder and attempted murder, rape and persecution.
The U.N. Security Council and concerned countries should impose targeted sanctions and an arms embargo, the group said.
Government spokesman Zaw Htay said no Myanmar government had ever been as committed to the promotion of rights as the current one.
"Accusations without any strong evidence are dangerous," he told Reuters. "It makes it difficult for the government to handle things."
The violence and the refugee exodus represent the biggest crisis the government of Nobel peace laureate Aung San Suu Kyi has faced since it came to power last year in a transition from nearly 50 years of harsh military rule.
Myanmar regards the Rohingya as illegal immigrants from Bangladesh and bouts of suppression and violence have flared for decades. Most Rohingya are stateless.
The United States and its Western allies imposed sanctions on Myanmar for years in support of Suu Kyi's campaign for democracy.
It has criticised the military campaign as "disproportionate" and called for an end to violence but an official of President Donald Trump's administration said this month he did not expect a return to sanctions.
Suu Kyi has faced scathing criticism and calls for her Nobel prize to be withdrawn. She denounced rights violations in an address to the nation last week and vowed that abusers would be prosecuted. She also said the government was trying to determine why so many people fled.
Seven U.N. experts, including Yanghee Lee, special rapporteur on rights in Myanmar, called on Suu Kyi to meet Rohingya to hear for herself the reasons for their exodus.
"No one chooses, especially not in the hundreds of thousands, to leave their homes and ancestral land, no matter how poor the conditions, to flee to a strange land to live under plastic sheets and in dire circumstances, except in life-threatening situations," they said.
They called on Myanmar to provide humanitarian access to Rakhine state, where the military has been restricting entry.
Suu Kyi has little, if any, control over the security forces under a military-drafted constitution that also bars her from the presidency and gives the military veto power over political reform.
Myanmar has seen a surge of Buddhist nationalism in recent years, and the public is supportive of the campaign against the insurgents.
Since Sunday, the army has unearthed the bodies of 45 members of Myanmar's small Hindu community who authorities say were killed by the insurgents soon after the violence erupted.
The Arakan Rohingya Salvation Army, which has claimed attacks on the security forces since October, denied killing the villagers.
Some Hindus have fled to Bangladesh. Others have taken refuge in Myanmar towns, accusing the insurgents of attacking them on suspicion of being government spies.