The denouncement and condemnation followed news that China was forming the so-called "Xisha District" and "Nansha District" on Vietnam’s Hoang Sa (Paracel) and Truong Sa (Spratly) Islands.  

Foreign Ministry spokeswoman Le Thi Thu Hang said in a statement Sunday that "Vietnam has full legal basis and historical evidence to affirm its sovereignty over the archipelagos."

"Vietnam's consistent stance is to strongly protest the formation of the so-called ‘Sansha City’ and related behavior as they seriously violate Vietnam's sovereignty, are unrecognized, have no value and are not beneficial to the friendly relationship between countries, while complicating the situation in the East Sea, the region and the world," Hang said.

The East Sea is known internationally as the South China Sea.

"Vietnam requests that China respect Vietnam's sovereignty, cancel wrong decisions that are relevant to such actions, and not repeat similar actions in the future," she said.

China announced Saturday the establishment of what it calls the "Xisha" and "Nansha" districts in Vietnam's Paracel and Spratly Islands.

The Chinese Ministry of Civil Affairs said that its State Council has approved the formation of "Xisha District" on Woody Island on the Paracels and "Nansha District" on the Fiery Cross Reef of the Spratlys.

China said the "Xisha District" would manage the Paracel Islands, the Macclesfield Bank and surrounding sea areas, while the "Nansha District" would manage Spratly Islands and surrounding sea areas.

China seized the Paracel Islands from South Vietnam by force in 1974, and has since been occupying them illegally. China also formed what's called the "Sansha City" on the Woody Island since 2012, with the intention of taking control of islands in the East Sea. China has also been illegally building artificial islands in recent years.

Vietnam has requested China many times to stop its illegal actions, which complicate the situation and threaten peace and stability in the East Sea. Last month, Vietnam sent a diplomatic note to the United Nations to protest China's unfounded sovereignty claims over the East Sea.