YANGON - Vietnam's prime minister told southeast Asian leaders on Sunday that China was slandering his country and committing dangerous violations in disputed waters, but the 10-nation ASEAN group refrained from criticising Beijing in a summit communique.
Tensions rose in the resource-rich South China Sea last week after China positioned a giant oil rig in an area also claimed by Vietnam. Each country accused the other of ramming its ships near the disputed Paracel Islands.
Hundreds of Vietnamese rallied in the country's biggest cities on Sunday to denounce China, in rare protests that looked likely to prolong the tense stand-off.
Speaking to fellow leaders of the Association of Southeast Asian Nations at a summit in Myanmar, Prime Minister Nguyen Tan Dung said Vietnam had acted with "utmost restraint" and used all means of dialogue to request China remove the rig.
"But until now, China not only hasn't responded to Vietnam's rightful request but also slandered and blamed Vietnam while increasing their violations, which are becoming more dangerous and serious," he said, in his strongest comments yet on the crisis.
China has accused Vietnam of intentionally colliding with its ships in the South China Sea, after Vietnam asserted that Chinese vessels used water cannon and rammed eight of its vessels at the weekend near an oil rig.
ASEAN, a loose grouping that relies on unanimous consensus to reach decisions, faced a test of unity at the summit as some members expressed alarm over China's growing assertiveness and pushed for a strong statement.
The group's foreign ministers voiced "serious concerns" on Saturday over the naval clashes between Vietnam and China and its top official urged Beijing to step up efforts to advance talks on maritime security.
ASEAN, however, appeared unwilling to risk antagonising China, which exerts huge political and economic influence over much of the region. Neither Myanmar President Thein Sein's opening speech nor the final statement of the summit on Sunday touched on the China-Vietnam dispute.
Dung urged ASEAN and other nations to "support the legal and legitimate requirements of Vietnam."
China's foreign ministry, in a statement late on Saturday, said the issue was not "a problem between China and ASEAN" and that it opposed certain member states trying to use it to sow discord. That was an apparent reference to Vietnam and the Philippines, two of the most vocal countries on the South China Sea dispute.
"The Chinese side is always opposed to certain countries' attempts to use the South Sea issue to harm the overall friendship and cooperation between China and the ASEAN," it said.
China was ready to work with ASEAN to continue implementing the Declaration on the Conduct of Parties in the South China Sea, a statement that was agreed in 2002 to try to manage tensions in the seas, the ministry added.
China has begun official talks with ASEAN to establish maritime conduct rules for the South China Sea, but argues that territorial disputes should be discussed on a bilateral basis. It claims the entire South China Sea, putting it in conflict with Taiwan, Vietnam, the Philippines, Malaysia, and Brunei. The last four are ASEAN members.