TOKYO (AP) — Japanese media say an exchange has lost 58 billion yen ($530 million) in cryptocurrency because of hacking.

The Coincheck exchange said on its website Friday that it had halted sales and withdrawals of the currency, which is called NEM. It later added that it had restricted dealings in most other cryptocurrencies too.

Kyodo News service reported that Coincheck President Koichiro Wada apologized at a news conference and said the company may seek financial assistance. Kyodo says the Coincheck exchange detected the unauthorized access to its system early Friday.

The reported loss tops the 48 billion yen that the Japan-based Mt. Gox Bitcoin exchange lost in 2014.