A rampaging mob set fire to a mosque and homes in a central Myanmar town, a police official said Wednesday, the latest outbreak of violence in communal unrest that has left at least 40 people dead. A week after Buddhist-Muslim clashes erupted, a mosque was torched in Nattalin town, 150 kilometres (90 miles) north of the country's commercial hub of Yangon, a police official who did not want to be named told AFP. A Nattalin resident said police were overwhelmed as a mob arrived in the town, setting fire to the mosque before leaving. "About 200 villagers came to the town last night. But the police could not control the mob... they destroyed the mosque and some houses. Then they left," the resident told AFP on condition of anonymity. A dusk-to-dawn curfew was imposed on three other towns, state media reported, as authorities tried to quell the violence, which flared last Wednesday in Meiktila, 130 kilometres north of capital Naypyidaw. Since then rioting has crept closer to Yangon, prompting the United States to warn against travelling to parts of the country. The clashes are a stark reminder of the challenge that Muslim-Buddhist tensions pose to Myanmar's government as it tries to reform the country after decades of iron-fisted military rule ended two years ago. UN envoy Vijay Nambiar, who recently visited Meiktila, told reporters on Tuesday that Muslim homes had been targeted "brutal efficiency". His comments chimed with the views of witnesses across the riot-hit area, who said the violence appeared to be organised. The clashes began on March 20, apparently triggered by an argument in a gold shop in Meiktila that turned into an escalating riot during which mosques were burned, houses razed and charred bodies left lying in the streets. Since then dozens of people have been detained in connection with the violence, which saw armed rioters -- including Buddhist monks -- roam the streets of Meiktila, threatening visiting journalists. It is the worst sectarian strife since violence between Buddhists and Muslims in the western state of Rakhine last year left at least 180 people dead and more than 110,000 displaced.