Vietnam has objected to China's reported move of laying undersea cables in the disputed Paracel Islands.
Vietnamese officials have said it is a violation to the country's sovereignty.
In Hanoi, Foreign Ministry spokeswoman Le Thi Thu Hang was asked about a BenarNews report on Monday, also carried by Radio Free Asia, that a Chinese ship was laying or repairing undersea cables near Chinese outposts in the Paracels, reported Radio Free Asia (RFA).
The reporting was based on commercial satellite imagery and vessel-tracking software, and was cited extensively by Vietnamese state media this week.
“Therefore, any activity relating to the two archipelagoes conducted without Vietnam’s permission are violations of its sovereignty and of no value,” she said.
U.S.-based experts interviewed by RFA said the cable work suggested that China was installing an undersea surveillance system for its occupied features in the Paracels, further militarizing the region.
Both Vietnam and China claim the Paracel Islands.