The exchange had planned to distribute small cash rewards of 2,000 won (US$1.40) or more to each user as part of a promotional event, but winners received at least 2,000 bitcoin each instead, media reports said.
“We would like to make it clear that this incident is unrelated to external hacking or security breaches, and there are no problems with system security or customer asset management,” Bithumb said in a statement.
Bitcoin prices briefly slumped 17 per cent to 81.1 million won on Friday evening on Bithumb, charts from the exchange show. It later recovered and last traded at 104.5 million won.
Bithumb trails Upbit, a dominant player in the South Korean crypto space.
