Surging maritime tensions dominated a meeting of Southeast Asian leaders Sunday, with Vietnam calling on its regional neighbours for support in its worsening territorial dispute with China.

The 10-member Association of Southeast Asian Nations (ASEAN) convened just days after both Vietnam and the Philippines locked horns with China in contested waters, stoking international alarm.

A joint statement from the summit, hosted for the first time by Myanmar in its showpiece capital Naypyidaw, was delayed after the meeting ended on Sunday, with sources saying a typing error meant the document had to be reconfirmed with member states.

Tensions in the South China Sea, which is criss-crossed by key shipping lanes and thought to contain vast energy reserves, loomed large over discussions and was expected to be noted in the final communique.

In remarks to the summit, Vietnam Prime Minister Nguyen Tan Dung urged his ASEAN counterparts to protest at China's controversial decision to move an oil drilling rig early this month into waters also claimed by Hanoi.

Reiterating accusations that Chinese vessels had then attacked Vietnamese ships in the disputed waters, he slammed Beijing's move as "extremely dangerous".

Dung also told the summit that Hanoi views the incident as a violation of international laws.

On Saturday ASEAN foreign ministers expressed "serious concerns over the ongoing developments" in a joint statement.

Disputes with China present a delicate challenge to the bloc, some of whose members are closely reliant politically and economically on Beijing.

In 2012 China's ally Cambodia caused consternation when it was ASEAN head by refusing to take Beijing to task over its assertive maritime stance.

- Protests erupt in Vietnam -

The latest incident has stoked bitter anti-China sentiment in Vietnam, with about 1,000 people joining one of the country's largest-ever rallies against Beijing in Hanoi on Sunday. Protests also broke out in two other major Vietnamese cities.

China and Vietnam, who fought a brief border war in 1979, frequently trade diplomatic barbs over oil exploration, fishing rights and the Spratly and Paracel Islands.

Vietnam's communist regime, which is wary of public gatherings that could threaten its authoritarian rule, has alternated between tolerating anti-China rallies and violently breaking them up.

Observers said Beijing's decision to move the rig could have been prompted by a visit to the region by US President Barack Obama, who reaffirmed support for Asian allies the Philippines and Japan, which is locked in its own maritime territorial dispute with China.

The move "underlines Beijing's commitment to test the resolve of Vietnam, its ASEAN neighbours and Washington," said the US-based Center for Strategic and International Studies.

UN Secretary General Ban Ki-moon called on both countries to "exercise the utmost restraint" in the sea, United Nations deputy spokesman Farhan Haq said Friday.

The South China Sea is claimed in part by ASEAN members Vietnam, the Philippines, Brunei and Malaysia as well as Taiwan.

Manila, which has asked a UN tribunal to rule on China's claims over most of the sea, also said on Wednesday it had detained a Chinese fishing boat in disputed territory.

Philippine President Benigno Aquino has also urged fellow Southeast Asian leaders to face up to the threat posed by China's increasing assertiveness in the sea.

Beijing prefers to negotiate directly with its smaller, weaker neighbours on a bilateral basis, a policy that is rejected by rival claimants.

The other ASEAN members are Cambodia, Indonesia, Laos, Myanmar, Singapore and Thailand.

Myanmar's chairmanship is the first time it has taken the helm of ASEAN, despite having been a member for 17 years, as concerns about the rights record of the former junta kept the country on the sidelines.

But reforms under a quasi-civilian regime that came to power in 2011 have burnished the country's international standing and seen the removal of most Western sanctions.

Thailand's contribution to the summit was overshadowed by the removal of Thai premier Yingluck Shinawatra from office for abuse of power in a court ruling last Wednesday that has brought rival protesters onto the streets of Bangkok.

In a statement by ASEAN foreign ministers, the bloc called for a "peaceful resolution" to the Thai crisis and stressed the importance of national reconciliation "in accordance with the will and interests of the people".