China has accused Indian troops of "crossing the boundary" in the Sikkim section, calling for their immediate withdrawal and a thorough investigation of the issue.
China has also stated that because of security reasons it has shut down Nathu La Pass for entry of Indian pilgrims for Kailash Mansarovar Yatra.
Chinese Foreign Ministry spokesman Geng Shuang claimed in a statement that the Indian border guards crossed the boundary in the Sikkim section of the Sino-India border and entered Chinese territory.
China urges India to immediately withdraw its border guards that have crossed the boundary and have a thorough investigation of this matter, Geng said.
The Sikkim section of the China-India boundary has been defined by treaties, Geng said, noting that the Indian government has repeatedly confirmed in writing that there is no objection to it.
The People's Liberation Army (PLA) had accused the Indian military of stopping the construction of a road in what it claims to be China's "sovereign territory" in the Sikkim section of the India-China border and said the move has "seriously damaged" border peace and tranquillity.
Geng's statement comes after tension mounted in a remote area of Sikkim following a scuffle between the personnel of the Indian Army and the PLA, leading to Chinese troops damaging bunkers on the Indian side of the border.
What sparked tension between the two nations:
The incident happened in the first week of June near the Lalten post in the Doka La general area in Sikkim after a face-off between the two forces, which triggered tension along the Sino-Indian frontier.
After the scuffle, the PLA entered Indian territory and damaged two make-shift bunkers of the Army.
Following the India-China war of 1962, the area has been under the Indian Army and the ITBP, which is the border guarding force and has a camp 15km from the international border.