The government, through its New Light of Myanmar newspaper, reports that riots erupted spontaneously in Rakhine, leaving 12 people dead and another 50 wounded. CNN reported Friday that at least 64 people have died this week in clashes between Buddhists and Muslims in the region.
Violence erupted along Myanmar's coastal area in June after the alleged rape and killing of a Buddhist woman. Buddhists retaliated by attacking Muslims. The United Nations estimates at least 78 people were killed during those clashes.
Thein Sein said there were some "persons or organizations" that were working "behind the scenes" in Rakhine.
With riots again erupting in the region, "effective measures will be taken for rule of law and community peace and tranquility with the collaborative efforts of Myanmar police force," he said.
U.N. Secretary-General Ban Ki-moon issued a statement through his spokesman's office saying communal violence in Rakhine was "deeply troubling."
"The vigilante attacks, targeted threats and extremist rhetoric must be stopped," his statement read. "If this is not done, the fabric of social order could be irreparably damaged."