Vietnam has reaffirmed its sovereignty over the disputed Spratly and Paracel islands in the South China sea.

The move comes just a day after China, another claimant to the islands, declared itself the undisputed master.

On Monday, the first day of a five-day visit to China by Vietnamese President Tran Duc Luong, the two countries signed a series of agreements but stayed clear of the disputed islands.

Vietnam and China have clashed twice over the Spratly Islands, in 1988 and 1992. The Spratlys is believed to sit atop vast reserves of oil and gas.

China seized the Paracels from Vietnam and now considers them part of the nearby island province of Hainan.

Both islands, seen as potential flashpoints in the region, are also claimed by Taiwan, Brunei, Malaysia and the Philippines.