Bank moves to close cryptocurrency exchange Cryptopia's New Zealand dollar trading accounts are bad news for Kiwi investors.

The exchange said that its bank had told it that it would close the accounts for its New Zealand dollar-tethered currency (NZDT) on February 9.

NZDT is used by New Zealand traders as a way into, and out of, cryptocurrencies on Cryptopia. It represents about 2 per cent of the trading on the platform.

Cryptopia has stopped accepting deposits into NZDT and customers who want to withdraw their funds will need to do so by February 9, unless another banking solution is found within that time.The exchange is also offering a competitive market rate to allow users holding NZDT to convert it to bitcoin.

"Due to the extremely short notice from the bank (and little opportunity to present our case and provide compliance documentation to demonstrate our commitment to the applicable regulations), we believe this is the best course of action to protect our users. While we are working hard to secure alternative banking services, we have to prepare for the possibility that there may be a period of time between this closure and being able to provide these services again in future," Cryptopia said in an update.

Users will still be able to buy and sell cryptocurrencies on other providers' platforms and then trade those currencies across Cryptopia.