See how China has spent tens of billions of dollars turning farm fields and seaports into military complexes on Hainan and remote outposts in the South China Sea.

Vietnam has protested against China's alleged detention of its fishermen and fishing vessels in the contested Paracel Islands in the busy South China Sea, a foreign ministry spokesperson said on Thursday.

Vietnam urged China to "immediately release the fishermen and fishing vessels that were illegally detained", the spokesperson told reporters in a regular press conference, without specifying how many people had been detained or when they had been detained.

Vietnam on Thursday requested China to fully respect its rights over the Paracel Islands and to release all illegally captured fishermen and vessels.