China has demanded India immediately remove troops from the border amid an increasingly tense stand-off in the remote frontier region beside the Himalayan kingdom of Bhutan.

The Chinese foreign ministry on Thursday said India had been building up troops and repairing roads along its side of the border next to the mountainous Indian state of Sikkim.

The stand-off ratchets up tension between the neighbours, who share a 2,175 mile (3,500km) frontier, large parts of which are disputed.

“It has already been more than a month since the incident and India is still not only illegally remaining on Chinese territory, it is also repairing roads in the rear, stocking up supplies, massing a large number of armed personnel,” said a foreign ministry statement from Beijing.

“This is certainly not for peace.”

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 north-eastern regions.

India has said it warned China that construction of the road near their common border would have serious security implications.

No country should underestimate the Chinese military’s confidence Chinese defence ministry

The Indian prime minister, Narendra Modi, is to visit China early in September for a summit of leaders from Brazil, Russia, India, China and South Africa.

Indian officials say 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 keep the stand-off from escalating, and that India’s ambassador to Beijing is leading the effort to find a way for both sides to back down without loss of face.

Chinese state media have warned India of a fate worse than the defeat it suffered in a brief border war in 1962. China’s military has held live fire drills close to the disputed area, it said last month. On Friday the official China Daily said in an editorial that China was not in the mood for a fight, noting how the stand-off had been “unusually restrained”.

“However, if good manners do not work, in the end it may be necessary to rethink our approach. Sometimes a head-on blow may work better than a thousand pleas in waking up a dreamer,” the English-language paper added.