The Chinese embassy in the Philippines on Wednesday protested Manila's legislative inclusion of some of China's islands and reefs in the South China Sea.
A controversial baseline bill that defines the Philippines' territorial waters had been signed into law, the Philippine government announced on Wednesday.
In a statement, the Chinese embassy "expresses strong opposition and solemn protest" to the legislation.
"Huangyan Island and Nansha Islands have always been parts of Chinese territory and the People's Republic of China has indisputable sovereignty over these islands and their adjacent waters," the statement said.
It said the claim to territorial sovereignty over Huangyan Island and Nansha Islands by the Philippines is "illegal and invalid."
The 2009 baseline bill was passed by both chambers of the Philippine Congress last month and has drawn strong protests from China.
Upon the bill's passage through the Congress, Chinese vice Foreign Minister Wang Guangya summoned the Charge d'affaires of the Philippine embassy in China, Maria Barber, to lodge a stern protest.
The Chinese government expresses its strong dissatisfaction and stern protest over the adoption of the bill that violated China's sovereignty, in defiance of the grave concern raised by and repeated protests from the Chinese government, said Wang.