'Complicating an already difficult relationship': China accuses Indian border guards of crossing into its territory

China has accused Indian border guards of crossing into its territory from the state of Sikkim on India's northeastern border with Tibet, the Chinese foreign and defence ministries have said, complicating an already difficult relationship.

Geng Shuang, a spokesman with China's foreign ministry, said Indian guards "obstructed normal activities" by Chinese forces on the border and called on India to withdraw immediately, according to a ministry statement late on Monday.

He urged India to respect China's territorial integrity and the border treaties signed by the two countries, and said China had already suspended official pilgrimages at the Nathu La Pass, which lies on the frontier between Sikkim state and Tibet.

A spokesman for the Indian Army declined to comment but said the army would issue a statement on Tuesday. India's defence ministry did not immediately respond to a request for comment.

Nathu La connects India to Hindu and Buddhist sites in the region and was the site of a fierce border clash between Chinese and Indian troops in 1967.

China's Defence Ministry said in a separate statement India's military had obstructed work on a road, a move it described as seriously threatening peace on the border.

"China is dedicated to developing bilateral relations, and will staunchly defend its legitimate rights," it said.

"China hopes India will meet it halfway, not do anything to complicate the border issues and jointly maintain the good momentum of relations," the defence ministry said.

Ties between China and India have long been frosty as a result of long-term territorial disputes, as well as Beijing's support of Pakistan, and Indian leaders declined to attend China's "Belt and Road" summit aimed at boosting regional economic and political ties last month.

Chinese President Xi Jinping told Indian Prime Minister Narendra Modi earlier this month that the two countries should work to "appropriately" manage their differences.

A visit in April by Tibetan spiritual leader the Dalai Lama, who Beijing brands a separatist, to a region controlled by India but claimed by China also stoked tensions between the two countries.

The Indian government has since taken steps to cool tensions, rejecting an Australian request to take part in joint naval exercises with the United States and Japan last month to avoid agonising China.

Modi is expected to visit China in September to attend a summit of the BRICS nations, which groups Brazil, Russia, India, China and South Africa.