YANGON (Reuters) - Hundreds of homes burned and gunfire rang out as sectarian violence raged for a fifth day between Rohingya Muslims and Buddhists in western Myanmar on Thursday, testing the country's nascent democracy.
Security forces struggled to stem Myanmar's worst communal unrest since clashes in June killed more than 80 people and displaced at least 75,000. The latest violence has spread over several towns, including commercially important Kyaukpyu, where a multibillion dollar China-Myanmar pipeline starts.
The violence is one of the biggest tests yet of a new reformist government that has vowed to forge unity in one of Asia's most ethnically diverse countries.
The United Nations called for calm in volatile Rakhine State, citing reports of hundreds of houses destroyed since Sunday and large numbers of people seeking refuge in over-crowded camps near the state capital, Sittwe.
"The U.N. is gravely concerned about reports of a resurgence of inter-communal conflict in several areas in Rakhine State which has resulted in deaths and has forced thousands of people including women and children to flee their homes," Ashok Nigam, U.N. resident and humanitarian Coordinator in Myanmar, said in a statement.
Access to Rakhine State was restricted and information hard to verify, but witnesses said at least three people were killed on Thursday, bringing this week's death toll to at least five. There were widespread unconfirmed reports of razed and burning homes, gunfights and Rohingya fleeing by boat.
A representative of the Wan Lark foundation, which helps ethnic Rakhine Buddhists, said local people told him trouble had flared in the early hours of Thursday in Kyauk Taw, a town north of the state capital, Sittwe.
"Fires started in Pike Thel village. About 20 houses were burned. There was gunfire reported and, as far as we know, three Rakhines were shot dead on the spot," Tun Min Thein told Reuters by telephone.
A senior official from the Rakhine State government also said three people had been killed in Kyauk Taw. Witnesses reported soldiers arriving and at least one road closed.
In Yathedaung, a town northwest of Sittwe, security forces opened fire in a Rohingya district and about 10 houses were burned, Tun Min Thein added, reporting what he had been told by locals. Fires also were seen in Pauktaw, a town east of Sittwe.
That followed violence in Kyaukpyu, about 120 km (75 miles) southwest of Sittwe, where official media said one person had been killed, 28 wounded and 800 houses burned down.
The area is crucial to China's most strategic investment in Myanmar: twin pipelines that will stretch from Kyaukpyu on the Bay of Bengal to China's energy-hungry western provinces, bringing oil and natural gas to one of China's most undeveloped regions.
Rohingyas are officially stateless. Buddhist-majority Myanmar's government regards the estimated 800,000 Rohingyas in the country as illegal immigrants from Bangladesh and denies them citizenship. Bangladesh has refused to grant Rohingyas refugee status since 1992.
Around 50 boats carrying Rohingyas were reported to have left the Kyaukpyu area on Wednesday and were spotted apparently heading for Sittwe, Tun Min Thein said.
It was unclear what set off the latest arson and killing that started on Sunday. In June, tensions had flared after the rape and murder of a Buddhist woman that was blamed on Muslims, but there was no obvious spark this time.
Sittwe was the scene of violence in June but has escaped the latest unrest. Thousands lost their homes in June and many Rohingyas left or were moved out of the town by the authorities.
Curfews were imposed in Minbya and Mrauk Oo north of Sittwe from Monday after violence there. It was unclear if the authorities had extended that to other areas.
Thein Sein's government has negotiated ceasefires with most ethnic rebel groups that have fought for autonomy for half a century but has done nothing to address the Rohingya problem.
Rights groups such as Amnesty International have called on Myanmar to amend or repeal a 1982 citizenship law to end the Rohingyas' stateless status.
(Reporting by Aung Hla Tun and Reuters staff reporters; Writing by Alan Raybould and Jason Szep; Editing by Nick Macfie)