Major crypto exchange OKEx on Friday has announced suspension of all withdrawals of cryptocurrencies on its platform indefinitely while other functions remain normal and stable. The OKEx officials said "one of the private key holders of the exchange is cooperating with a public security bureau in investigations."

OKEx revealed that it has lost contact with an employee who is “co-operating” in a Chinese government investigation. In a notice published by OKEx the concerned key holder has being out of touch prevented withdrawal authorization from being completed. The exchange exercised a clause on its Terms of Service that says, “OKEx may change the Service and/or may also interrupt, suspend or terminate the service at any time with or without prior notice.”

OKEx apologized for any inconvenience caused by the suspension of digital assets/cryptocurrencies withdrawals.The exchange tried to eliminate the fear of security breach and assure users that their funds and assets remain safe.

OKEx is industry's fourth-largest on-chain BTC. Following the suspension, OKEx’s native token OKB has crashed 15%. Bitcoin (BTC) has also fallen by nearly 3%.

Hours before the announcement, on-chain transaction monitoring service Whale Alert noted several large transfers between OKEx and unknown wallets. OKEx founder Mingxing Xu reportedly been questioned by the police as per the reports by Chinese news agency Caixin.

Beijing based reporter Colin Wu wrote,"the OTC merchant on OKEx had mistakenly received 500,000 CNY from the fraud group and was hunted by the police across the provinces.”