Myanmar's national leader Aung San Suu Kyi, facing outrage over violence that has forced about 370,000 Rohingya Muslims to flee to Bangladesh, will not attend the upcoming United Nations General Assembly because of the crisis, her office said on Wednesday.

The exodus of refugees, sparked by security forces' fierce response to a series of Rohingya militant attacks, is the biggest problem Suu Kyi has faced since becoming Myanmar's leader last year. Critics have called for her to be stripped of her Nobel Peace Prize for failing to do more to end the killings.

In her first address to the UN General Assembly as national leader in September last year, Suu Kyi defended her government's efforts to resolve the crisis over treatment of the Muslim minority. This year, her office said she would not be attending because of the security threats posed by the insurgents and her efforts to restore peace and stability.

"She is trying to control the security situation, to have internal peace and stability, and to prevent the spread of communal conflict," Zaw Htay, the spokesperson for Suu Kyi's office, told Reuters.

Htay also said Kyi would address the nation on reconciliation and peace next Tuesday. 

MYANMAR-ROHINGYA/BANGLADESH

Rohingya refugee children carry an old woman in a sling near Balukhali makeshift refugee camp in Cox's Bazar, Bangladesh. On Tuesday international media reported on one man who carried both his elderly parents, in baskets slung over his shoulders, nearly 100 kilometres to safety. (Danish Siddiqui/Reuters)

International pressure has been growing on Buddhist-majority Myanmar, also known as Burma, to end the violence in the western state of Rakhine that began on Aug. 25 when Rohingya militants attacked about 30 police posts and an army camp. The attacks triggered a sweeping military counter-offensive against the insurgents, whom the government has described as terrorists.

But refugees say the security operation is aimed at pushing Rohingya out of Myanmar. They, and rights groups, paint a picture of widespread attacks on Rohingya villages in the north of Rakhine state by the security forces and ethnic Rakhine Buddhists, who have put many Muslim villages to the torch.

UN Security Council calls for end to the violence

The 15-member Security Council met behind closed doors on Wednesday, at the request of Sweden and Britain, to discuss the crisis for the second time since it began and agreed to publicly condemn the situation. 

The council "expressed concern about reports of excessive violence during the security operations and called for immediate steps to end the violence in Rakhine, de-escalate the situation, re-establish law and order, ensure the protection of civilians ... and resolve the refugee problem." 

Stuck in no man's land between Bangladesh and Myanmar0:40

British UN Ambassador Matthew Rycroft said it was the first statement from the Security Council on Myanmar in nine years. Such statements have to be agreed on by consensus and Russia and China have traditionally protected Myanmar from any action. 

Myanmar said last week it was negotiating with Russia and China to ensure they blocked any censure by the Security Council over the violence in Rakhine state.

'Ethnic cleansing'

UN Secretary General Antonio Guterres said the situation in Rakhine was "catastrophic" and best described as ethnic cleansing

"When one-third of the Rohingya population had to flee the country, could you find a better word to describe it?" he told a news conference. "I call on the Myanmar authorities to suspend military action, end the violence, uphold the rule of law, and recognize the right of return of all those who had to leave the country," said Guterres, adding that he had spoken several times with Myanmar's national leader Suu Kyi.

The United Nations' top human rights official earlier this week denounced Myanmar for conducting a "cruel military operation" against the Rohingya, branding it "a textbook example of ethnic cleansing."

176 Rohingya villages now empty

In the latest violence reported by the government, the insurgents attacked and burned three police posts in the north of Rakhine on Tuesday. There were no reports of casualties.

Htay told reporters 176 ethnic Rohingya villages are now empty after all the residents fled during the recent violence.

There had been a total of 471 Rohingya villages in three townships, Htay said, and some people fled from another 34 villages.

Myanmar Attacks

Spokesperson for Myanmar's State Counsellor's Office Zaw Htay talks to journalists during a press briefing at the Presidential Palace in Naypyitaw, Myanmar, Wednesday. Zaw Htay said Myanmar would not allow all people who fled to return. (Associated Press)

He also said Myanmar would not allow all people who fled to return. "We have to verify them. We can only accept them after they are verified." 

But authorities have denied that the security forces, or Buddhist civilians, have been burning Rohingya villages, and have blamed the insurgents instead. Nearly 30,000 Buddhist villagers have also been displaced, they say.

Despite worries that a humanitarian crisis is unfolding, Myanmar has rejected a ceasefire declared by the Arakan Rohingya Salvation Army insurgents to enable the delivery of aid there, saying it did not negotiate with terrorists.

China backs Myanmar

Bangladesh says all of the refugees will have to go home and it has called for safe zones in Myanmar to enable them to do so. But China, which competes with the United States for influence in the Southeast Asian nation, said on Tuesday it backed Myanmar's efforts to safeguard "development and stability."

The military, which ruled with an iron fist for almost 50 years until it began a transition to democracy in 2011, retains important political powers and is in full control of security. While Suu Kyi and her civilian government have no say over security, critics say she could speak out against the violence and demand respect for the rule of law.

A statement from Global Affairs said Tuesday that Canada is "deeply concerned" about the treatment of the Rohingya in Myanmar. 

"Canada firmly reminds State Counsellor Aung San Suu Kyi and the military leadership of their duty to work together and act responsibly in the face of the current humanitarian crisis," the statement said.

"The violence must end now. The Rohingya should be respected and recognized in the country. To deny their rightful place in Myanmar only weakens the democratic vision Aung San Suu Kyi has fought so hard for throughout her life."

Bangladeshi border guards block Rohingya refugees0:58

But anti-Rohingya sentiment is common in Myanmar, where Buddhist nationalism has surged since the end of military rule. Suu Kyi, whom the military blocked from becoming president and who says Myanmar is at the beginning of the road to democracy, could risk being denounced as unpatriotic if she were seen to be criticizing a military operation that enjoys widespread public support.

More aid desperately needed: UN

The exodus to Bangladesh shows no sign of slowing with the number of refugees rising to 400,000, according to the latest UN estimate. Many refugees are hungry and sick, without shelter or clean water in the middle of the rainy season.

"We will all have to ramp up our response massively, from food to shelter," George William Okoth-Obbo, assistant high commissioner for operations at the UN refugee agency, told Reuters during a visit to a refugee settlement in Bangladesh.

Two emergency flights arrived in Bangladesh on Tuesday with aid for about 25,000 refugees. More flights are planned with the aim of helping another 120,000, the UN agency said. 

With files from The Associated Press and CBC News