Singapore-based Bitfufu, backed by Chinese mining rig giant Bitmain, has filed claims for $11.7 million against crypto exchange FTX, which has revealed it owes more than $3 billion to its largest creditors as its bankruptcy process gets under way.

The claims were submitted by Bitfufu’s subsidiary Ethereal Tech last week, according to Kroll, a U.S. restructuring administration firm appointed by FTX. The company is among 13 unsecured creditors that has so far handed in claims against the collapsed crypto empire founded by former billionaire Sam Bankman-Fried.

Bitfufu was established in 2020 with investment from Bitmain, founded by crypto pioneer Jihan Wu, and is led by former members of the company. The startup, which offers services including sales, rental and hosting of bitcoin mining machines, announced in January that it is merging with a special purpose acquisition company to go public in the U.S. at a valuation of $1.5 billion.