Bitcoins worth Rs 20 crore were stolen from one of India’s top cryptocurrency exchanges. The Delhi-based Coinsecure filed a police complaint on Thursday, saying 438 bitcoins that were stored offline were stolen from the company.

The crime is being dubbed India’s biggest cryptocurrency theft, so far, according to The Economic Times.

Coinsecure has accused its Chief Scientific Officer Amitabh Saxena of siphoning off the money from the company’s wallet and urged the government to seize his passport to stop him from fleeing the country. It realised that the bitcoins had been stolen after finding that all the cryptocurrency it had stored offline had vanished. It later found that users’ private keys, which are the passwords it stored offline, were leaked online and led to the hack.

Trying to trace the hackers proved futile as the data logs of the affected wallets had been wiped off. This means Coinsecure has no idea where the bitcoins were transferred. No bitcoins were mined on the company’s website since it confirmed the theft on Thursday.

“We regret to inform you that our bitcoin funds have been exposed and seem to have been siphoned out to an address that is outside our control,” Coinsecure said on its website, adding that all customers who suffered losses because of the breach will be compensated from the company’s funds.

The Delhi Police have registered a case under the Information Technology Act. The Cyber Cell has seized the company’s servers to check the extent of the system breach and whether more wallets have been compromised. It has summoned senior security officials of Coinsecure for questioning.

The government and the Reserve Bank of India have repeatedly warned traders against dealing in virtual currencies.