The world body estimates that more than 1,000 people may already have been killed in the violence.
The U.N. High Commissioner for Refugees said the estimated number of Rohingya who fled to Bangladesh since violence erupted in Myanmar on August 25 had risen from 164,000 on Thursday, after aid workers found big groups in border areas.
Myanmar's de facto leader Aung San Suu Kyi is to miss next week's UN General Assembly as criticism of her handling of the Rohingya crisis grows.
The government of Myanmar, formerly known as Burma, blames terrorists for starting the recent violence.
A Myanmar reporter in the north of the state said he had reports from residents of an area called Rathedaung that six villages there had been torched and that there had also been shooting in the area.
"I've joined the rally to express my solidarity with the Rohingya people", activist Mahfuza Haque Neela told CNN.
A large number of Muslims, including women and children, have been burnt alive, lynched to death or lost their lives while fleeing the ethnic cleansing of the Rohingya people.
Congressional leaders from both parties are adding their voices to the global condemnation of the violence in western Myanmar that has sent an estimated 164,000 Rohingya Muslims fleeing to Bangladesh and led to growing doubts about Suu Kyi's leadership. It said the 15-member committee would work on implementing recommendations made last month by a commission led by former U.N. Secretary-General Kofi Annan.
According to the United Nations, up to 300,000 Rohingya could be displaced in Bangladesh due to "clearance operations" carried out by the Tatmadaw, Myanmar's armed forces.
But anti-Rohingya sentiment is common in Myanmar, where Buddhist nationalism has surged since the end of military rule.
Congressional aides said they do not expect renewed economic sanctions on Myanmar because lawmakers remain wary of taking steps that might set back democratic and economic reforms. The protest was led by the youth wing of the predominantly Muslim Malaysia's ruling party, the United Malays National Organisation, after Friday prayers.
In Indonesia, hundreds of protesters gathered near the famous Borobudur temple in Central Java, and hundreds more outside the Myanmar Embassy in Jakarta. Since the emergence of ARSA, Suu Kyi's government has hardened its position on the Rohingya plight, saying that extremist elements pose a security risk.
"But what some have called "ethnic cleansing" and others "a slow genocide" has persisted - and recently accelerated".
"If the political price of your ascension to the highest office in Myanmar is your silence, the price is surely too steep", said Tutu, who became the moral voice of South Africa after helping dismantle apartheid there.
Presidential office spokesman Zaw Htay said Ms Suu Kyi will miss the assembly, which opened on Tuesday and runs until 25 September, to address domestic security issues.
US Ambassador to UN Nikki Haley said in a statement issued here yesterday that over the past week, conditions in Rakhine have continued to deteriorate.
There is very limited access to the north of Rakhine State and few if any independent witnesses, raising fears that a humanitarian crisis could be unfolding among Rohingya still there.
Dean, the other contributor on the panel, said that the Rohingya Muslims are "on the bottom of the barrel", and are "one of the most abused groups of people in the world". The predominantly Buddhist Myanmar considers them Bangladeshi but Bangladesh says they are from Myanmar, CNN reported.
In response, the military intensified "clearance operations", driving thousands of people from their homes.
In northern Rakhine state there are reports of at least another 30,000 Rohingyas trapped in hilly terrain without basic supplies of food, water or medicine, according to activists.
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