Myanmar prepares to welcome world leaders as it hosts the Association of Southeast Asian Nations (ASEAN) summit for the first time since the country began introducing political reforms nearly four years ago.

US President Barack Obama, Indian Prime Minister Narendra Modi, his Japanese counterpart Shinzo Abe and Chinese Prime Minister Li Keqiang will join ASEAN leaders in the capital Naypyidaw for the crucial meet that comes amid territorial disputes in the South China Sea.

Fresh discussions on a festering regional maritime row in the South China Sea are likely to be aired, with Southeast Asian nations including Vietnam and the Philippines looking for US support in their claims to waters contested with regional powerhouse China.

The sea route is of tremendous strategic importance to everyone, including Washington, as a third of the world's shipping transits through the contested sea. It is also rich with fish and is believed to have large oil and gas reserves under the seabed.

China - which claims most of the area - has stepped up naval patrols in recent months and temporarily positioned an oil rig in territory also claimed by Vietnam, sparking deadly anti-Chinese riots. Taiwan, Brunei and Malaysia also lay claim to parts of the sea.

The meetings begin between ministers from Southeast Asia and will be expanded on Thursday to include leaders from the Russia, China, India, Japan and South Korea among others.

Obama is set to meet Myanmar President Thein Sein and opposition leader and fellow Nobel laureate - Aung San Suu Kyi during his two night stay in the country, as he looks to show his support for landmark elections slated for late 2015.

Al Jazeera's Marga Ortigas, reporting from Naypyidaw, said: "Myanmar is stepping into a diplomatic spotlight here, the largest gathering of world leader it has ever seen."

"There will still be much focus on maritime tensions but aside from that, there will be talks on larger economic integration as well. They plan to be one economic community by 2015. They hope to come up with more formalised statement by the end of the summit," she said.

Prosecution of Rohingya

Under Thein Sein, a reformist former general, the country has been welcomed back into the international fold after enacting sweeping reforms including the release of most political prisoners and the promise of free and fair polls next year.

The reforms have seen most sanctions lifted, while foreign investment has poured into the South Asian nation of about 60 million people.

But Suu Kyi has sought to temper US "over-optimism" over Myanmar's reform process in comments just days before Obama's arrival.

Wrangles over the constitution, the cramping of media freedom as well as tinderbox issues such as burgeoning Buddhist extremism and anti-Muslim violence, have taken the sheen off its emergence from isolation after decades of iron-fisted army rule and raised fears its reforms are slipping.

Though not expected to be part of the official dialogue, mistreatment of the country's 1.3 million Rohingya Muslims in the predominantly Buddhist nation has captured headlines worldwide.

More than 100,000 Rohingya have fled the country by boat in the last two years. Another 140,000 are living under apartheid-like conditions in displacement camps.