China said India needs to observe the treaty and pull back troops immediately from Doklam.
China said on Monday that the Sino-India border in the Sikkim sector is well demarcated and the Indian Army's action there is a "betrayal" of the position taken by successive Indian governments.
"Former Indian Prime Minister Jawaharlal Nehru endorsed the 1890 Sino-British Treaty on Sikkim in a letter to the then Chinese counterpart Zhou Enlai in 1959. Successive Indian governments have also endorsed this," Chinese foreign ministry spokesman Geng Shuang said at a media briefing.
"The India-China boundary in the Sikkim section is well demarcated. The action taken by India is a betrayal of the position taken by the Indian governments," he said.
The spokesman, however, said the line for diplomatic communication between the two sides is "open and smooth".
On the likelihood of a meeting between Prime Minister Narendra Modi and President Xi Jinping during the G20 Summit in Hamburg, Germany, Geng said he has "no information to offer at the moment" about the arrangements for bilateral meetings between Xi and leaders of other countries.
China has accused Indian troops of transgressing into the Doklam area of the Sikkim sector, which it claims as a part of its territory.
Bhutan also claims the area as a part of its territory.
China also said it has closed the Nathu La route in Sikkim for Kailash Mansarovar pilgrims from India.
"The other route to Tibet through Lipulekh pass is open as it is located in the middle section where there is no dispute, Geng said.
The Chinese foreign ministry also dismissed Defence Minister Arun Jaitley's remarks that India of 2017 is different from what it was in 1962, saying China too is different and will take "all necessary measures" to safeguard its territorial sovereignty.
Jaitley who responded to China's oblique reference to the war the two countries had fought 55 years ago and asking India to learn from "historic lessons", had said, "If they are trying to remind us, the situation in 1962 was different and India of 2017 is different." He had also said that the current standoff between Indian and Chinese troops in the Sikkim sector was triggered by Beijing.
Responding to Jaitley's remarks, Chinese foreign ministry spokesman Geng Shuang said, "He is right in saying that India in 2017 is different from 1962, just like China is also different."
Geng also accused India of using Bhutan as a "cover up" for the "illegal entry" into the Doklam area over which Bhutan has lodged a protest with the Chinese government.
"In order to cover up the illegal entry of the Indian border troops, to distort the fact and even at the expense of Bhutan's independence and sovereignty, they try to confuse right from wrong, that is futile," Geng said.
He said China has "no objection to normal bilateral relations between India and Bhutan but firmly opposed to the Indian side infringing on Chinese territory using Bhutan as an excuse."
"The Bhutan side does not know previously that the Indian troops entered into the Doklam area, which is not in line with what is claimed by the Indian side," Geng said.
Asked whether any talks are going on between India and China to resolve the Sikkim standoff, Geng said, "After the illegal entry of border took place, China has lodged solemn representations at different levels with the Indian side in Delhi and Beijing."
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