"China's actions have violated Vietnam's sovereignty over the Paracels Archipelago, Vietnam's sovereign rights to the continental shelf, the 200-nautical-mile Exclusive Economic Zone, going against the spirit of the Declaration of the Code of Conduct in the South China Sea (...)," said government spokeswoman Nguyen Phuong Nga.

Nga said since late May, China had been sending the M/V Western Spirit seismic survey vessel, together with escort ships, to conduct seismic studies in the Tri Ton Island area and in oil and gas exploration lots 141, 142 and 143 on Vietnam's continental shelf, approximately 90 - 116 nautical miles (167 - 214 kilometres) from Ly Son Island of Quang Ngai province.

China has also been carrying out ground leveling on Tri Ton Island for construction works on this island, Nga said.

Vietnam's foreign ministy raised the matter several times withEeijing, but "China is continuing those activities," Nga said.

China has occupied the Paracels since 1974 when its troops overwhelmed a South Vietnamese garrison occupying the islands. China has seized hundreds of Vietnamese fishermen fishing near the Paracels for the past years for "infringing China's territory."

Both Vietnam and China are signatories to the 2002 Declaration on the Conduct of Parties in the South China Sea. It commits the parties to resolving the islands' status through negotiations and provides for freedom of navigation.

The US Secretary of State Hillary Rodham Clinton in July called on the Association of South-East Asian Nations and China to reach agreement on a full code of conduct in the South China Sea to prevent conflicts.

She also pushed for proper settlement of the South China Sea issue through multilateral negotiations, but China rebuffed as saying it favoured a bilateral negotiations.

The South China Sea is believed to contain substantial undersea oil reserves.

Deutsche Presse Agentur - August 6, 2010