NEW DELHI - India's foreign ministry said on Thursday it has lodged a "strong protest" with China for issuing stapled visas to some Indian citizens instead of stamped ones, reviving an old irritant in the strained relations between the Asian giants.

Arindam Bagchi, India's foreign ministry spokesperson, said some Indian athletes who were heading to a sporting event in China were given such stapled visas rather than stamped visas, reigniting an issue leaders of the two countries have discussed in the past.

The practice of issuing visas on loose sheets of paper has been seen as China's way of questioning India's sovereignty over some states situated on the border of both nations.

"There shall be no discrimination or differential treatment on the basis of domicile or ethnicity in the visa regime for Indian citizens," Bagchi said at his weekly media briefing.

"India reserves the right to suitably respond to such actions," he said.

Beijing has in the past issued stapled visas to residents of India's northeastern state of Arunachal Pradesh, saying it was disputed territory and part of southern Tibet.

New Delhi rejected the claim, saying Arunachal Pradesh has always been a part of India.

China and India have been uneasy neighbours for decades following a war on their disputed Himalayan frontier in 1962. Their relations nosedived in 2020 after a border clash in which 20 Indian and four Chinese soldiers were killed.

This year, China ratcheted up tensions by giving Chinese names to 11 locations in Arunachal Pradesh.

(Reporting by Rupam Jain; Editing by YP Rajesh and Bernadette Baum)