BEIJING -  Vice Foreign Minister Zhang Zhijun summoned Vietnamese Ambassador to China Nguyen Van Tho on Thursday to lodge a solemn representation to the Vietnamese side concerning the recent passing of a Vietnamese maritime law that extends the country's jurisdiction to islands claimed by China.

The Vietnam National Assembly on Thursday passed the "Vietnamese Law of the Sea," which describes China's Xisha Islands and Nansha Islands in the South China Sea as being within Vietnam's sovereignty and jurisdiction.

Reaffirming that China has indisputable sovereignty over the Xisha Islands, Nansha Islands and their adjacent waters, Zhang said the law infringes upon China's sovereignty.

"China strongly protests and firmly opposes such a move by Vietnam," he said.

Vietnam's unilateral action has complicated and escalated the problem and violated the consensus reached by both leaders, as well as the spirit of the Declaration on the Conduct of Parties in the South China Sea (DOC), said Zhang.

"Vietnam's action is illegal, invalid and detrimental to peace and stability in the South China Sea," said Zhang, adding that China will firmly safeguard its national sovereignty.

China requests Vietnam to immediately rectify its mistakes and refrain from taking any action that could damage bilateral relations or jeopardize the peace and stability of the South China Sea, said Zhang.

On the same day, the Foreign Ministry issued a declaration to protest the law.

The declaration states that it is unlawful and invalid for any other country to claim sovereignty over the Xisha Islands and the Nansha Islands.