YANGON (Reuters) - Several more villages were burned down on Saturday in a part of northwest Myanmar where many Rohingya Muslims had been sheltering from violence sweeping the area, two sources monitoring the situation said. The fires, which started on Friday when up to eight villages went up in flames in the ethnically mixed Rathedaung region, have increased concerns that more minority Rohingya will flee to neighboring Bangladesh. Blazes started on Saturday engulfed as many as four more settlements in Rathedaung, likely destroying all the Muslim villages in the area, the sources said.  Slowly, one after another villages are being burnt down - I believe that Rohingyas are already wiped out completely from Rathedaung,  said Chris Lewa of the Rohingya monitoring group, the Arakan Project.  There were 11 Muslim villages (in Rathedaung) and after the past two days all appear to be destroyed.  It was unclear who set fire to the villages, located in a part of northwest Myanmar far from where Rohingya insurgents attacked 30 police posts and an army base last month, triggering an army counter-offensive in which at least 400 people have been killed. Independent journalists are not allowed into the area, where Myanmar says its security forces are carrying out clearance operations to defend against  extremist terrorists .  Human rights monitors and fleeing Rohingya say the army and ethnic Rakhine vigilantes have unleashed a campaign of arson aimed at driving out the Muslim population. Some 290,000 people have fled across the Bangladeshi border in less than two weeks, causing a humanitarian crisis. Rathedaung is the furthest Rohingya-inhabited area from the border with Bangladesh and aid workers are concerned that a large number of people were trapped there. The sources said that among the torched villages was the hamlet of Tha Pyay Taw. They were also concerned about the village of Chin Ywa, where many people sheltering from other burnings in the area had been hiding and two other settlements. On Friday, the villages of Ah Htet Nan Yar and Auk Nan Yar, some 65 km (40 miles) north of Sittwe, capital of Rakhine state, were also burned along with four to six other settlements. One source, who has a network of informers in the area, said 300 to 400 Rohingya who had been hiding at Ah Htet Nan Yar were now in the forest or attempting a perilous, days-long journey by foot in the monsoon rain toward the River Naf separating Myanmar and Bangladesh. Myanmar leader Aung San Suu Kyi said on Thursday her government was doing its best to protect everyone, but she has drawn criticism for failing to speak out about the violence and the Muslim minority, including calls to revoke her 1991 Nobel Peace Prize. The country s Rohingya Muslims have long complained of persecution and are seen by many in Buddhist-majority Myanmar as illegal migrants from Bangladesh. 