The Ministry of Foreign Affairs has condemned China for releasing a map and announcing its so-called 12th Five-Year-Plan of National Oceanic Development, in which it claims sovereignty over Vietnam's Truong Sa (Paracel) and Hoang Sa (Spratly) archipelagoes.
Ministry spokesman Luong Thanh Nghi said Wednesday the map and the plan are totally valueless.
"Vietnam affirms its indisputable sovereignty over the Hoang Sa and Truong Sa archipelagoes, sovereignty and jurisdiction rights over the exclusive economic zone and continental shelf in the East Sea as is laid out in the 1982 United Nations Convention on the Law of the Sea," Nghi said.
He told the press the release of the map and the announcement of the plan seriously violated Vietnam's sovereignty.
He added that such actions breach international law and an agreement on basic principles guiding the settlement of sea-related issues between Vietnam and China, and are not in line with the spirit of the Declaration on the Conduct of Parties in the East Sea (DOC).
Such actions raise tensions and complicate the situation in the East Sea, he said.
Southeast Asian leaders are set to wrap up a summit on Thursday dominated by efforts to defuse tensions over the East Sea, internationally known as the South China Sea, AFP reported.
The 10-member Association of Southeast Asian Nations (ASEAN) endured deep divisions last year over how to handle rows with China over the sea, and leaders have been focused at this week's talks in Brunei on rebuilding unity, the newswire said.
China and four ASEAN members including Vietnam, the Philippines, Malaysia and Brunei all claim territory in the East Sea.
China's claim is the largest, covering most of the sea's 648,000 square miles (1.7 million square km), a move that has been emphatically rejected by international scholars.
The area is thought to hold vast untapped reserves of oil and natural gas that could potentially place China, the Philippines, Vietnam and other claimant nations alongside the likes of Saudi Arabia, Russia and Qatar.
A slew of squabbles between China and ASEAN claimants in the disputed East Sea have prompted protracted negotiations on a formal code of conduct aimed at easing tensions in the waters.
In 2002 the parties involved issued the political Declaration of Conduct (DOC) and China finally agreed in July 2011 to guidelines for its implementation, saying it was open to "different formulas and initiatives.
China has proposed that ASEAN and Beijing hold a special meeting to hasten progress on the code of conduct
But analysts said a legally binding robust code of conduct (CoC) is just off the Chinese radar of interest.
"Information regarding the proposed talks between ASEAN and China on a CoC is vague, including dates. I do not expect a major breakthrough on this issue any time soon," said Ian Storey, a maritime expert with the Institute of Southeast Asian Studies in Singapore.
Philippine President Benigno Aquino said Wednesday he was nevertheless happy ASEAN was now at least united in trying to ensure the disputes did not "become bloody", AFP reported.
"So there is unity of purpose and one can always be hopeful that that will lead to something more concrete," he was quoted by the newswire as saying.