A Chinese naval ship is visiting Ho Chi Minh City, state media said Wednesday, as the US and Vietnam continue a separate week-long naval exchange amid rising tensions in the South China Sea.

The Chinese vessel, which arrived in Vietnam's southern port city Monday on a three-day visit, will carry out "professional exchanges to share experience and foster friendly relations," the official Vietnam News Agency said.

In central Danang city, the US and Vietnam are on the third day of pre-planned "non-combatant" naval exchange activities, which will include disaster control training aboard the guided missile destroyer USS Chafee.

On Tuesday, Vietnam said it held indisputable sovereignty over the Paracel and Spratly Islands, responding to what it said was a new Chinese drive to implement "a nationwide plan for islands protection."

The new plan "seriously violates Vietnam's sovereignty over the two archipelagoes" and China must "immediately cancel" the effort, said foreign ministry spokesman Luong Thanh Nghi.

China and South Vietnam once administered different parts of the Paracels but after a brief conflict in 1974 Beijing took control of the entire group of islands.

Vietnam holds several of the larger Spratly Islands which China claims, and the neighbouring countries have recently been locked in a string of diplomatic rows over their conflicting claims.

Most recently, a Vietnamese fisherman alleged that he had been beaten and kept in harsh conditions during seven weeks in Chinese detention for what Beijing said was illegal fishing off the Paracel Islands.

British Foreign Secretary William Hague on Wednesday urged a solution to the regional disputes in the South China Sea.

"We look for a peaceful resolution of those differences in line with international law," he told reporters in Hanoi.

China says it has sovereign rights to the South China Sea, believed to sit atop vast oil and gas deposits, including areas close to the coastlines of other countries and hundreds of kilometres from its own landmass.

The disputed region is a key trading route for the US, which has opposed Beijing's attempts to settle conflicting claims bilaterally, repeatedly calling instead for the peaceful resolution of disputes.