Bitcoins worth more than $70 million (more than Rs 451 crore) were stolen after hackers carried out a heist at a leading digital currency platform NiceHash – a Slovenia-based crypto-mining exchange, BBC reported. The company said it had suspended its operations for a day and was trying to recover the stolen bitcoins for its users.

NiceHash provides a platform for users to mine for other cryptopcurrencies and get paid in Bitcoin. The breach took place early on Wednesday, the company’s Chief Executive Officer Marko Kobal said, according to BBC. The hackers made away with nearly 4,700 bitcoins, he added.

“We would not exist without our devoted buyers and miners all around the globe, the company said in a statement. “We understand that you will have a lot of questions, and we ask for patience and understanding while we investigate the causes and find the appropriate solutions for the future of the service. We will endeavour to update you at regular intervals,”

The theft comes as the price of bitcoin soared through the week, crossing $17,000 for the first time on Thursday.

NiceHash has informed bitcoin exchanges and mining sites about the breach in order to track and recover stolen currency. The authorities believe the hackers used the credentials of one of the company’s engineerss to enter the NiceHash system.

“Given the complexity and security of the systems in place, this appears as an incredibly coordinated and highly sophisticated attack,” Kobal said, according to CNN.

The company’s head of marketing, Andrej Skraba, told Reuters that the attack was probably made from an IP address outside the European Union.