HANOI • Vietnam has protested against China's actions, saying the latter had established two administrative units on islands in the South China Sea, in Beijing's latest move to demonstrate its assertiveness in the disputed waters.

China has recently been pushing its presence in the energy-rich waters while other claimants are pre-occupied with tackling the coronavirus pandemic, prompting the United States to call on China to stop its "bullying behaviour" there.

Last Saturday, China said that it had established an administrative district on the Paracel Islands and another on the Spratly Islands.

The two districts are under the control of China's Sansha city, according to China Global Television Network.

"The establishment of the so-called Sansha city and related activities seriously violated Vietnam's sovereignty," Vietnam Foreign Ministry spokesman Le Thi Thu Hang said in a statement on Sunday.

"Vietnam demands that China respect Vietnam's sovereignty and abolish its wrongful decisions," she said in the statement.

A Chinese government survey ship was seen earlier last week tagging an exploration vessel operated by Malaysia's state oil company, Petronas, in the disputed waters, and remained offshore of Malaysia as of late Sunday.

Earlier this month, Vietnam lodged an official protest with China after the sinking of a Vietnamese fishing boat it said had been rammed by a China Coast Guard vessel near the Paracel Islands.

China claims 90 per cent of the potentially energy-rich South China Sea, but Brunei, Malaysia, the Philippines, Taiwan and Vietnam also lay claim to parts of it. About US$3 trillion (S$4.3 trillion) of trade passes through the strategic waterway each year.

REUTERS