HANOI, Vietnam – Chinese authorities have been holding 21 Vietnamese fishermen and two boats detained near the Paracel Islands since March 3rd, a Vietnamese official said Wednesday (March 21st).

It is the latest incident as the two countries battle over the South China Sea islands. China has controlled the Paracels – known as Hoang Sa Islands in Vietnamese – since 1974, but Vietnam continues to claim them.

"The captain spoke to his family and told them the Chinese are demanding 70,000 yuan ($11,000) for their release," Pham Thi Huong of the People's Committee of Ly Son Island told AFP, saying it wasn't clear if the price was for one or both boats.

Officials have advised the family not to pay.

Last week, Vietnam's Foreign Ministry said China "seriously violated" its sovereignty by allowing a local oil company to open bidding for exploration near the Paracels. China claims sovereignty over nearly all the South China Sea.