Myanmar's national leader Aung San Suu Kyi, facing outrage over ethnic violence that has forced about 370,000 Rohingya Muslims to flee to Bangladesh, will not attend the upcoming U.N. 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 halt the strife.

In her first address to the U.N. 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 spokesman for Suu Kyi's office, told Reuters

International pressure has been growing on Buddhist-majority Myanmar 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, who 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.

But authorities have denied that the security forces, or Buddhist civilians, have been setting the fires, 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.

The Trump administration has called for protection of civilians, and 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".

PUBLIC SUPPORT

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.

But anti-Rohingya sentiment is common in Myanmar, where Buddhist nationalism has surged since the end of military rule.

Suu Kyi, who 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 criticising a military operation that enjoys widespread public support.

The U.N. Security Council is to meet on Wednesday behind closed doors for the second time since the latest crisis erupted. British U.N. Ambassador Matthew Rycroft said he hoped there would be a public statement agreed by the council.

However, rights groups denounced the 15-member council for not holding a public meeting. Diplomats have said China and Russia would likely object to such a move and protect Myanmar if there was any push for council action to try and end the crisis.

The exodus to Bangladesh shows no sign of slowing with the number of refugees rising to 370,000, according to the latest U.N. estimate on Tuesday.

Bangladesh was already home to about 400,000 Rohingyas.

Many refugees are hungry and sick, without shelter or clean water in the middle of the rainy season. The United Nations said 200,000 children needed urgent support.

Two emergency flights organised by the U.N. refugee agency arrived in Bangladesh on Tuesday with aid for about 25,000 refugees. More flights are planned with the aim of helping 120,000, a spokesman said.

Muslim-majority Indonesia sent four aircraft to Bangladesh on Wednesday with 34 tonnes of tents, rice, water and blankets. President Joko Widodo, at a military base to see the flights off, told reporters more would be sent.