SEOUL, South Korea (AP) — A South Korean cryptocurrency exchange says hackers have stolen about one-third of the coins traded on its market.

Coinrail's announcement Monday sent bitcoin prices tumbling to a two-month low.

Coinrail said hackers stole cryptocurrencies including Pundi X, Aston and NPER. It did not give the value of the stolen coins but Yonhap News agency cited unnamed industry sources saying about coins worth about 40 billion won ($37 million) were lost.

Bitcoin was trading at $6,780, down from more than $7,500 before the weekend, according to Coindesk, which monitors prices.

Coinrail said it was cooperating with police and suspended trading.