India on Thursday said an unmanned aerial vehicle (UAV) had "crossed over" the border with China in the Sikkim sector after losing contact with the ground control due to some technical problem.
The defence ministry said the Indian border security personnel, as per standard protocol, immediately alerted their Chinese counterparts to locate the UAV and they later reverted with its location.
In Beijing, the Chinese defence ministry said the Indian drone recently "intruded" into its airspace and crashed in the Sikkim sector, prompting it to lodge a diplomatic protest with
India over the violation of China's territorial sovereignty.
The defence ministry here said the exact cause of the incident is under investigation.
Sources said the UAV belonged to the Indian Army.
The incident comes to light days before Chinese Foreign Minister Wang Yi's visit here to attend the Russia-India-China trilateral meeting.
"An Indian UAV which was on a regular training mission inside the Indian territory lost contact with the ground control due to some technical problem and crossed over (to) the LAC in the Sikkim Sector," the defence ministry said in a statement.
It further said, "As per standard protocol, the Indian border security personnel immediately alerted their Chinese counterparts to locate the UAV. In response, the Chinese side reverted with the location details of the UAV."
It did not clarify when the incident happened.
"The matter is being dealt with in accordance with the established protocols through institutional mechanisms to deal with situations along the India- China border areas," it said.
Chinese Foreign Ministry spokesman Geng Shuang said the country has lodged a diplomatic protest with India over the drone violating Chinese sovereignty.
The armies of India and China were engaged in a 73-day- long standoff in Dokalam after Indian troops stopped Chinese soldiers from building a key road in the area. The face-off had ended on August 28. Dokalam is located in the Sikkim section of the India-China border.