BEIJING (Reuters) - China accused India on Wednesday of “concocting” excuses over the illegal entry of the South Asian nation’s military into Chinese territory on their disputed border, adding that China had shown great restraint.

FILE PHOTO: Indian Prime Minister Narendra Modi (L) and Chinese President Xi Jinping leave after a group picture during BRICS (Brazil, Russia, India, China and South Africa) Summit in Benaulim, in the western state of Goa, India, October 16, 2016. REUTERS/Danish Siddiqui/File Photo

The stand-off on a plateau next to the mountainous Indian state of Sikkim, which borders China, has ratcheted up tension between the neighbors, who share a 3,500-km (2,175-mile) frontier, large parts of which are disputed.

Early in June, according to the Chinese interpretation of events, Indian guards crossed into China’s Donglang region and obstructed work on a road on the plateau.

The two sides’ troops then confronted each other close to a valley controlled by China that separates India from its close ally, Bhutan, and gives China access to the so-called Chicken’s Neck, a thin strip of land connecting India and its remote northeastern regions.

India has said it warned China the road construction would have serious security implications.

In a statement, China’s Foreign Ministry said the Indian military was still in Chinese territory, and that China had acted with a great deal of restraint, demanding that India withdraw its forces.

“But the Indian side not only has not taken any actual steps to correct its mistake, it has concocted all sorts of reasons that don’t have a leg to stand on, to make up excuses for the Indian military’s illegal crossing of the border.”

The ministry reiterated that the border had been agreed in 1890 by the governments of China and Britain, India’s colonial ruler until 1947, and later with the Indian government.

India’s actions are not only a serious encroachment of Chinese territory, but a challenge to regional peace and stability and normal international order, it added.

The Indian foreign ministry made no immediate response.

But a government source contradicted a separate Chinese statement that suggested a thinning of Indian forces at the disputed site, saying there had been no change.

“The strength remains the same as it was, it’s status quo,” said the source, declining to be named in line with government policy.

In the separate statement, China’s Foreign Ministry said more than 40 Indian border troops and one bulldozer remained on Chinese territory by late July, down from a figure of more than 400 earlier who had advanced more than 180 m. (197 yards) into its territory.

Indian officials have previously said about 300 soldiers from either side are facing each other about 150 meters (yards) apart on the plateau.

They have told Reuters that both sides’ diplomats have quietly engaged to try to ensure the stand-off does not escalate, and that India’s ambassador to Beijing is leading the effort to find a way for both sides to back down.