- China's defence ministry accused India of violating its airspace
- The army said the drone lost contact with ground control
- India, China ended border stand-off in Doklam three months ago
The incident is being investigated, the army said today, asserting that it was handling the episode "in accordance with established protocol" in border areas.
"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 the LAC (Line of Actual Control) in the Sikkim Sector," the army 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. The exact cause of the incident is under investigation. 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," the statement added.
China's defence ministry had accused India of violating its airspace and conveyed "dissatisfaction".
"The Indian move violated China's territorial sovereignty. We strongly express our dissatisfaction and opposition," the deputy director of the Chinese army's western theatre combat bureau, Zhang Shuili, said in a statement.
Chinese border troops "took a professional and responsible attitude" and carried out identification verification of the device, said Mr Zhang.
"We will earnestly fulfil our mission of duty and firmly defend the sovereignty and security of our country," he added.
Chinese military's western theatre command jurisdiction covers almost all of the 3488-km LAC, including Tibet's border region with India and the Ladakh region.
Three months ago, the neighbours ended one of their worst border stand-offs in decades.
In August, the two nations pulled back their troops to resolve a tense two-month deadlock over part of a Himalayan plateau claimed by both China and Bhutan. The standoff began in mid-June after Chinese troops started building a road on the remote Doklam plateau. India, citing concerns about territorial integrity, moved soldiers into the flashpoint zone to halt the work, prompting Beijing to accuse it of trespassing.
After both sides withdrew, India's army chief said in September that his country could not afford to be complacent and must be prepared for war.