Six Vietnamese fishermen have been detained by Chinese naval ships on Thursday in the latest fallout in the disputed waters of the South China Sea.

Vietnamese state-media reported that the fishermen were detained along with their boat near the disputed Paracel Islands. However, China’s Foreign Ministry released a statement saying the boat was operating illegally when the fishermen were picked up near the undisputed coastal area of China’s southern Hainan Island, adding Vietnam needs to educate fishermen about Chinese territories. 

The detention is likely to add to the growing tension between Beijing and Hanoi, which are engaged in a territorial dispute after a Chinese oil rig was positioned roughly 120 miles off Vietnam’s coast and in a special economic zone designated by Vietnam, an area over which both countries claim jurisdiction.

The geopolitical dispute quickly manifested among its people, setting off anti-Chinese riots starting in what turned out to be a Taiwanese-owned factory. The movement escalated violently, killing several Chinese nationals and eventually drove out many Chinese expatriates. While the xenophobic riots have stopped, officials from both sides have called for negotiations to avoid future problems.