China removed an old bunker of the Indian Army located at the tri-junction of India, China and Bhutan in Sikkim by using a bulldozer after the Indian side refused to accede to its request to dismantle it, according to official sources.

The incident that took place in June first week in Doka La general area in Sikkim led to a face-off between the two forces, triggering tension in the Sikkim section of the border, the sources said on Wednesday.

China is believed to have not taken kindly to India building many new bunkers and upgrading older ones along the border in Sikkim in the recent past to augment its defences against the People’s Liberation Army (PLA), the sources said.

Of the 3,488-km-long border from Jammu and Kashmir to Arunachal Pradesh, a 220-km section falls in Sikkim.

Beijing is also upset with New Delhi over the recent visit of the Dalai Lama to Arunachal Pradesh, the sources said, adding they were also trying to escalate tension in the forward areas, including in Sikkim, even though the border in the Northeastern State is demarcated.

The Sikkim government has sent a report to the Central government giving details of the situation along the border following the stand-off in Doka La.

The first batch of Kailash Mansarovar pilgrims, comprising about 50 people, returned from the Nathu La border post as the stand-off between India and China continues.

The pilgrims returned to Gangtok on June 23 after staying in Nathu La for three days awaiting permission from the Chinese side to undertake onward journey.

The second batch did not move from Gangtok while pilgrims were told to go home as the Kailash Mansarovar pilgrimage is unlikely to continue this year via Nathu La.

The Sikkim route to Mansarovar, which is in Tibet, was thrown open to public in 2015.

The visas for the third batch, comprising about 50 pilgrims, are not given yet. A total of 8-10 batches were supposed to go for the pilgrimage through Nathu La this year.

Union Home Secretary Rajiv Mehrishi said on Tuesday that 100 pilgrims were sent back by China despite they having a Chinese visa.

The sources said the Chinese side has mentioned a broken bridge as being the reason for the pilgrims not being able to cross into Tibet for the annual yatra.

Sikkim is a part of the middle sector and experts have been warning the government of increased Chinese activities in this area.

China on Wednesday termed the construction of a road in the Sikkim sector “legitimate”, asserting that it was being built on Chinese territory that neither belongs to India nor Bhutan and no other country has the right to interfere.

China on Tuesday lodged a protest with India over the alleged “crossing of boundary” by its troops in the Sikkim sector and demanded their immediate withdrawal, as Beijing warned that future visits of Indian pilgrims to Kailash Mansarovar will depend on the resolution of the standoff.

The last such transgression happened in Sikkim in November 2008 when Chinese soldiers destroyed some makeshift Indian Army bunkers there.