The Indian government has issued a legal notice to halt the “unethical” auction by Sothebys of ancient gem relics, which it said should be treated as the sacred body of the Buddha.The auction, which has prompted an outcry from scholars and monastic leaders, is scheduled for 7 May, and the gems are expected to sell for about HK$100m (£9.7m).

Its ministry of culture said the auction of the Piprahwa gems in Hong Kong this week “violates Indian and international laws, as well as United Nations conventions”, and demanded their repatriation to India “for preservation and religious veneration”.

The legal notice has been served on Sotheby’s Hong Kong and Chris Peppé, one of three heirs of William Claxton Peppé, a British colonial landowner who in 1898 excavated the gems on his estate in northern India, who are selling the relics.

Unearthed in 1898 by British estate manager and engineer William Claxton Peppé, the relics were discovered inside a sandstone coffer within the Piprahwa stupa, widely believed to be the ancient city of Kapilavastu, the Buddha’s childhood home. Among the contents were five reliquaries, including one of rock crystal with a fish-form handle, containing nearly 1,800 gemstones, precious metal sheets, bone, and ash.

An inscription in late Mauryan Brahmi script—deciphered by scholars Vincent Smith and later Harry Falk—affirmed the relics belonged to the Shakya clan and held the corporeal remains of the Historical Buddha. This epigraphic evidence, combined with early Pali texts like the Mahāparinibbāna-sutta, makes Piprahwa the only authenticated site of Buddha’s relics confirmed through inscription.

Following the discovery, a portion of the relics was presented to King Rama V of Siam (Thailand), and enshrined at Wat Saket in Bangkok, Shwedagon Pagoda in Yangon, and in Sri Lanka. The Indian Museum in Kolkata holds the majority of the gemstones, but the Peppé family retained a portion—approximately one-fifth—which is now coming to market.