Coincheck says that hackers stole deposits of NEM customers, the lesser-known digital currencies.
The trading site pledged to use cash from its own funds to pay 46.3 billion yen (US $ 426 million) to cover user losses. The amount is about 20 percent less than the total value of stolen virtual money.
Coincheck said in a blog post that hacking has caused huge pressure for customers, other exchange sites, and people across the cryptocurrency industry.
"We expressed our deepest and simplest apology to all those involved," the company said.
The company has now stopped trading in all virtual currencies other than Bitcoin. Meanwhile, NEM prices slumped nearly 20 percent after the theft was revealed last weekend, but has since recovered from the loss.
On the other hand, Coincheck does not respond to repeated requests to comment on how exactly the funds will be used for customer refunds.
SEOUL - South Korea's intelligence agency said the North Korean hacker could be behind the theft of 530 million dollars worth of virtual coin from a cryptocurrency exchange in Japan last month. It was expressed by South Korean intelligence agencies to MPs as revealed by a number of parties who know the problem.
People, who have knowledge of the parliamentary intelligence committee process, told Reuters on Tuesday (6/2/2018) that the National Intelligence Service did not show evidence that North Korean hackers were responsible for one of the largest criptocurrency theft in history but marked it as a possibility.
Local media had earlier reported the intelligence agency told an intelligence committee that North Korean hackers might have hacked into a Tokyo-based stock exchange.
"This is a possibility that North Korea is behind the theft," said one of the people who spoke with Reuters.
The person said the virtual coin market remains the main target of North Korean hackers because of the size and lightness of regulations. But there is no solid evidence that North Korea is responsible.
Last month, Coincheck, one of the largest criptocurrency bourses in Japan, said that 58 billion yen ($ 530 million) worth of NEM virtual coins were stolen and would return 46.3 billion yen to investors who have lost money. This is possible, but not a scenario that may be supported by evidence that North Korea is behind the theft, "another source spoke with Reuters.
The two sources who spoke to Reuters declined to be named because of the sensitivity of the problem. A spokesman for NIS declined to comment.
The report has rekindled Pyongyang's speculation of releasing cyber attacks. The US has publicly blamed North Korea for launching a WannaCry cyber attack that crippled hospitals, banks and other companies around the world by 2017.
A South Korean lawmaker on Monday said that North Koreans are responsible for the loss of billions of cryptocurrencies due to the theft of a local cryptocurrency exchange by 2017.
"North Korea sends hacking emails to criptocurrency exchanges and their customers' personal information and steal (cryptocurrency) worth billions of won," Kim Byung-kee, a member of South Korea's parliamentary intelligence committee, said Monday.
But Kim did not disclose which cryptocurrency exchange was hacked.