(reuters) -- The crisis over the security forces' [operations against] Rohingya is the biggest problem Suu Kyi has faced since becoming Myanmar's leader last year. Critics have called for Suu Kyi 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 party spokesman said she would not be attending, although he said he was unsure why.

"She's never afraid of facing criticism or confronting problems. Perhaps she's got more pressing matters here to deal with," Aung Shin, the spokesman, told Reuters.

International pressure has been growing on Myanmar to end the violence in the western state of Rakhine.

Reports from refugees and rights groups paint a picture of widespread attacks on Rohingya villages in the north of Rakhine by the security forces and ethnic Rakhine Buddhists, who have put numerous Muslim villages to the torch.

But Myanmar authorities have denied that the security forces, or Buddhist civilians, have been setting the fires, instead blaming the insurgents. Nearly 30,000 Buddhist villagers have also been displaced, they say.

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 to be created 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. Suu Kyi has no say over those matters.

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. 

(Photo: Myanmar State Counsellor Aung San Suu Kyi, REUTERS)