YANGON (Reuters) - Myanmar leader Aung San Suu Kyi’s security adviser told diplomats on Tuesday that a U.N. mission looking into allegations of rape, torture and killings of Rohingya Muslims would only “aggravate” troubles in the western state of Rakhine.

A Myanmar border guard police officer takes pictures at the remains of a burned house in Tin May village, northern Rakhine state, Myanmar July 13, 2017. Picture taken July 13, 2017. REUTERS/Simon Lewis

Myanmar has declined to grant visas to three experts appointed by the United Nations in May to look into allegations of abuses against the powerful armed forces.

Last week, the U.S. ambassador to the United Nations in New York, Nikki Haley, called on Myanmar to accept the mission, which was mandated in a Human Rights Council resolution.

“We dissociated ourselves from the decision because we found that it was less than constructive,” said National Security Adviser Thaung Tun, speaking to U.N. officials and diplomats, including U.S. Ambassador Scot Marciel.

The decision of other countries - including China and India - to join Myanmar in distancing themselves from the resolution was a “principled stand”, Thaung Tun said.

“We feel that that mission can only aggravate the situation on the ground,” he said.

The treatment of the roughly one million Muslim Rohingya has emerged as majority Buddhist Myanmar’s most contentious rights issue as it makes a transition from decades of harsh military rule.

The Rohingya are denied citizenship and classified as illegal immigrants from Bangladesh, despite claiming roots in the region that go back centuries, with communities marginalized and occasionally subjected to communal violence.

The government denounces the violence but has done little to improve the lot of the Rohingya.

‘INCREASING TERRORIST ACTIVITY’

The European Union proposed the investigation after the U.N. High Commissioner for Human Rights said the army’s operation in the northern part of Rakhine State - where most people are Rohingyas - likely included crimes against humanity.

Troops fanned out to villages after Rohingya militants killed nine policemen in attacks on border posts in October. The operation sent an estimated 75,000 people across the nearby border to Bangladesh, where many gave accounts of abuses.

Reuters was among international media escorted to the area last week in a tour closely overseen by security forces.

Rohingya women told reporters of husbands and sons arbitrarily detained, and of killings and arson by security forces that broadly match the accounts from refugees in Bangladesh.

Myanmar has largely denied the accusations, and says most are fabricated.

Thaung Tun did not directly address the allegations, but said Myanmar had a “clear right to defend the country by lawful means” as it tackles “increasing terrorist activities”.

Officials say a domestic investigation, led by Vice President Myint Swe, a former lieutenant general, is sufficient.

A commission headed by former U.N. chief Kofi Annan is looking into the problems in Rakhine State, but is not tasked with investigating rights abuses.

Thaung Tun said the government had started implementing interim recommendations the panel proposed in March, which included shutting camps where more than 120,000 Rohingya have languished since communal violence five years ago.