The situation surrounding China's decision to send an oil rig into waters disputed with Vietnam is growing unpredictable, a Vietnamese legislator said Tuesday.

Members of the Vietnamese National Assembly met Tuesday in Hanoi to discuss a decision by China National Offshore Oil Corp. to deploy rig HD-981 about 120 miles off the coast of Vietnam.

National Assembly Chairman Nguyen Sinh Hung said the situation in the South China Sea was getting complicated.

"China's recent deployment of a giant oil rig and its protective armada in Vietnam's [exclusive economic zone] seriously violates Vietnam's territorial sovereignty," he said.

A government report submitted Tuesday to the assembly says Vietnam reserves the right to maintain a posture of self-defense in the event the situation escalates.

China says it's operating within its territorial waters. The U.S. government has weighed in, saying it has no stance on claims to the South China Sea, but China was acting provocatively in the disputed waters.

The Chinese government this week began evacuating its nationals from Vietnam in response to ongoing anti-China demonstrations.

Vietnam and China lock horns over sea row
Naypyidaw, Myanmar (AFP) May 20, 2014 - Vietnamese and Chinese officials have locked horns over a maritime dispute that sparked deadly rioting in Vietnam, with Hanoi's defence minister Tuesday saying the neighbours have yet to reach any agreement.

Tensions remain high in the region after an eruption of anti-China rage in Vietnam over Beijing's controversial plans to drill for oil in contested waters, in which angry mobs last week attacked hundreds of foreign-owned businesses, killing two Chinese nationals.

China responded by evacuating thousands of its citizens from Vietnam, as relations between the neighbours sank to their lowest levels in decades.

Vietnamese defence minister Phung Quang Thanh said the two sides had discussed the placement of the giant rig in the disputed territory and stressed the need for a "peaceful resolution" to the row during meetings .

"We still have different point of views," he told reporters during meetings of Association of Southeast Asian Nations defence ministers in the Myanmar capital Naypyidaw on Tuesday, which were also attended by China.

Informal ministerial talks were dominated by the South China Sea, which is also claimed in part by ASEAN members the Philippines, Brunei and Malaysia as well as Taiwan.

Last week leaders of the 10-nation bloc presented a rare united front by expressing "serious concern" over disputes in the waters, which are home to key shipping lanes and thought to contain vast energy reserves.

Washington has also warned about the potential for tensions to escalate.

ASEAN defence ministers had a "frank and candid exchange of views on regional and international security", according to a statement released Tuesday after the meeting.

Myanmar Defence Minister Wai Lwin told reporters that talks between Vietnam, China and the Philippines were "constructive".

"Vietnamese authorities understand that the situation can affect their economy," he said, adding that Thanh had insisted that "they can control the situation".

Fearing an impact on vital foreign investment, Vietnamese authorities deployed hundreds of security personnel in the streets leading to the sprawling Chinese embassy in Hanoi on Sunday, restricting access to the neighbourhood and other suspected protest sites.

The authoritarian communist regime usually limits expression of public discontent.

But the violence and scope of the riots that left some 140 people injured and spread across dozens of provinces, appeared to have taken the country by surprise.

Dozens of Chinese and Vietnamese vessels have engaged in repeated skirmishes near the rig, including reported rammings and the use of water cannon.