Vietnamese Deputy Prime Minister Vu Duc Dam made it clear he is unhappy with China's actions in the waters near his country.

"Recently, peace, stability and maritime navigation in the (South China Sea) has been seriously threatened," Dam said in his speech on the first day of the conference.

"Vietnam strongly desires peace," the deputy prime minister said. "China has blatantly deployed a deep-water oil rig escorted by a hundred ships, including naval forces and military aircraft deep within the exclusive economic zone of Vietnam."

China's activities, he argued, "constitute a serious infringement of international law."

He said his country would try to resolve its issues with China "in line with international law."

"In Vietnam, we are thankful for the support of the many countries who raised concerns about China's actions," the deputy prime minister said. "The conflict does not only affect Vietnam; the South China Sea is so important for the world."

On maintaining development, Dam said regional cooperation is essential. "The recent global financial crisis and economic downturn pointed to the fact that all economies need to strengthen their sustainability and resilience," he said.

Coming challenges include ensuring sustainable growth and resolving regional imbalances in terms of economic growth and social and cultural developments, Dam said.

The emergence of interregional free-trade agreements such as the Trans-Pacific Partnership and Regional Comprehensive Economic Partnership would help to underpin stability, he said.

Dam also pointed to the need to develop regional transport infrastructure, tackle climate change, and cooperate on developing technology and building the skills of Asia's population.

"It is easy to fall for the temptation of trading growth for (the health of the) environment," he said. But "in the long term, the entire region and the world will suffer the consequences."