China has cancelled plans to jointly launch commemorative stamps with India, an apparent reflection of strained relations over a military standoff at the Asian neighbours’ border.

China’s State Post Bureau had planned with India to jointly launch a stamp in April commemorating 2020 as the 70th year of bilateral relations and a special stamp showing the Mogao Caves, a renowned site in China’s Gansu province where the Buddhist grottoes reflect the two countries’ cultural links.

The Post Bureau announced on its website on Tuesday that these plans had been cancelled. It did not elaborate.

Diplomatic relations between China and India have been tense since June, when at least 20 Indian soldiers were killed in the western Himalayas after being attacked by Chinese troops using rocks and clubs.