The account balances of some customers of cryptocurrency trading platform Coinbase fell to zero on Wednesday, the company confirmed, as it moved to assure them that their assets were still there.

Dozens of accounts had posted on social media sites including X earlier in the day, with screenshots that appeared to show their Coinbase account balance had fallen to zero.

"We are aware that some users may see a zero balance across their Coinbase accounts and may experience errors in buying or selling," the firm told AFP by email shortly after the news broke.

"Your assets are safe," it added.

The incident came on the same day that bitcoin -- the world's best-known and most valuable digital currency -- broke through the symbolic $60,000 barrier for first time since November 2021.

News of the incident hit the Coinbase's shares hard on Wall street: After rising as much as 6.5 percent in early trading to reach the highest level for two years -- the company's share price slipped to close just 0.8 percent higher.

In a later update posted on its website and shared with AFP, Coinbase said activity on the site was "starting" to normalize.

"We will continue to monitor our systems and provide updates," it added.