China again urges India to immediately withdraw its border guards that have crossed the boundary, Chinese Foreign Ministry spokesperson Geng Shuang said on Monday.

The Sikkim section of the China-India boundary has been defined by the Anglo-Chinese Convention of 1890, Geng said, noting that the Indian government has repeatedly confirmed that there is no objection.

"It is the basic principle of international law to abide by the treaty," said Geng. The Indian side has violated the existed treaty by crossing the border, which also goes against the United Nations Charter and basic principle of international law. Geng noted that "it is a very serious issue."

China urges India to respect boundary treaties and China's territorial sovereignty, and immediately withdraw the border guards.