Customers of a little-known Canadian cryptocurrency exchange are set to lose all their coins after hackers allegedly made off with around $6m, although some suspect an exit scam.

MapleChange took to Twitter on Sunday morning to claim that it had “sustained a hack” and was investigating the issue.

“Due to a bug, some people have managed to withdraw all the funds from our exchange. We are in the process of a thorough investigation for this,” it continued in a separate tweet soon after. “We are extremely sorry that it has to come to end like this. Until the investigation is over, we cannot refund anything.”

The firm confirmed that it was unable to refund any Bitcoin or Litecoin funds, but that it was trying to do so for other currencies, asking customers to PM their details.

“We are sending all of the coin developers the wallets containing the coins we have left. So far, LMO and CCX have been handed over the funds,” it said.

Around 913 BTC ($5.8m) was apparently ‘stolen’ in the raid, with some reports suggesting that this might actually be an exit scam.

Although the firm still appears to be active on Twitter, its domain is now defunct.

“There is no incentive for using small exchanges. Use established exchanges that are regulated, & transparent,” tweeted cryptocurrency analyst, Joseph Young.

“Small exchanges also focus on maximizing profitability, not security or investor protection.”

Changpeng Zhao, CEO of the world’s biggest Bitcoin exchange, Binance, argued that customers should steer clear of exchanges which don’t store funds in cold wallets. These are typically more secure than hot wallets as they’re not connected to the internet.

“Avoid using exchanges that doesn't have anything in their cold wallets,” he tweeted.

It’s unclear how many customers MapleChange has, but its Twitter account has less than 2,000 followers, versus 236,000 for Binance’s Zhao.