Another ten Vietnamese fishermen have been detained by the Chinese around the Hoang Sa (Paracel) Islands April 14, while 12 others taken last month have not been returned.
In the latest case, the fishing crew sailing with captain Mai Phung Luu, were all from the island district of Ly Son in the central province of Quang Ngai.
The families of the men have received phone calls saying the Chinese are demanding a ransom of 70,000 Yuan (US$10,250) per person, the district People's Committee was quoted by newswire Vnexpress as saying Sunday.
China has not returned 12 Quang Ngai fishermen caught on March 22 though Vietnam Foreign Ministry on March 29 requested an unconditional release. The same ransom has been demanded for them.
The families of the 12 fishermen have lost contact with them for nearly a month.
Chinese patrols are constantly detaining Quang Ngai fishermen when they fish or take shelter from rough seas around the Hoang Sa Archipelago, over which Vietnam has proved its historic sovereignty.
Four cases involving 107 fishermen were reported in Quang Ngai last year. All of them were released, some after two months. In many cases, their boats, equipment and catch were not returned.