They may resemble other ATMs, but officials are increasingly warning about the potential for fraud with the expanding fleet of cryptocurrency ATMs popping up across the country.

The National Consumers League says the largely unregulated machines have become favored by scammers for their anonymity and irreversibility — once a user transfers or deposits funds, that money is essentially gone.

The FTC says consumers should contact banks or other institutions directly about any account issues. And it warns consumers not to believe anyone who says they must use a crypto ATM to address a financial problem.

“Real businesses and government agencies will never do that — anyone who does is a scammer,” the agency said.