China on Thursday said India had infringed upon the country's territorial integrity in the Sikkim sector.
Even as it warned India of "far worse consequences" if found that the drone had entered Chinese airspace with "hostile intentions", it added, "It (India) needs to apologise to China".
Sun Shihai, a researcher at the Chinese Academy of Social Sciences, said the talks, which were initiated in 2003, had become an important channel for communication between top Chinese and Indian diplomats on a wide range of issues beyond the border dispute itself. "At the same time, the foreign ministers of the three countries will also exchange views on global and regional issues of common concern".
Beijing often referred to the 1890 Britain-China treaty during the lengthy Dokalam standoff, stating that it has defined the Sikkim section of the boundary with Tibet, therefore the border in that area has been settled.
The claim was first made by Zhang Shuili, deputy head of the combat bureau of China's Western Theater Command's joint staff department, who said an Indian unmanned aerial vehicle had recently intruded into China's airspace and crashed.
The allegations were also quoted by Xinhua news agency, saying that the falling of the drone has "violated China's territorial sovereignty".
As late as August, India had rushed troops to Doklam Plateau and although an immediate conflict was avoided, heated rhetoric on both sides has soured relations.
The Chinese have reverted with the location details of the UAV.
"We will fulfil our mission and responsibility and defend China's national sovereignty and security resolutely", he said.
"These actions show India's provocative attitude and China has the full right to respond as it sees fit based on the results of the investigation", the editorial also said.
In June, Donald Trump authorized sales of two dozen maritime reconnaissance drones to India-with an estimated price tag of $3 billion-to help counter China's growing influence in the Indian Ocean.
Geng did not spell out when the incident had taken place.