China has fined Bitmain, one of the world’s largest producers of cryptocurrency mining machines, almost 25 million yuan (US$3.6 million) for alleged tax violations, according to tax authorities in Beijing.

The Beijing office of the State Tax Administration said on its website that it fined Bitmain on 4 April for failing to comply with personal income tax rules.

The department sent Bitmain a violation notice in August last year, but the company failed to withhold and pay about 16.6 million yuan of income tax.

Bitmain did not immediately respond to Forkast’s request for comment.

Founded in 2013, Bitmain is widely known for its Antminer series. On Tuesday, Nasdaq-listed US crypto-mining company CleanSpark said it had purchased 45,000 new Antminer S19 XP blocks for $144.9 million to double its current bitcoin mining capacity, with all blocks due for delivery to Bitmain by the end of September.