Hackers behind last week's $530 million cryptocurrency heist - one of the biggest ever - have started trying to sell some of the stolen "XEM" coins, the vice president of the foundation behind the digital currency said on Tuesday.

Jeff McDonald of the NEM Foundation, which is behind the XEM cryptocurrency, said he had traced the stolen coins to an unidentified account, and that the hackers had begun trying to spend the coins on six exchanges.

The location of the account was not yet known and McDonald could not yet confirm how much of the stolen coins had been spent.

"He is trying to spend them on multiple exchanges. We are contacting those exchanges," Singapore-based McDonald told Reuters.

Hackers made off with roughly 58 billion yen ($532.6 million) from Tokyo-based cryptocurrency exchange Coincheck Inc late last week, raising questions about security and regulatory protection in the emerging market of digital assets.

XEM is the world's 10th biggest cryptocurrency. As of 1601 GMT, XEM was trading at around $0.83 per coin, according to trade website Coinmarketcap, with a total market value of around $7.5 billion.