BRUSSELS—EU data commissioners have said that the United Kingdom would be treated as a “third country” in the event of a “no-deal” Brexit next March and have confirmed that data transfers would be “restricted.”

“Until the European Commission rules that data protection in the U.K. is on a par with that in the EU, the U.K. will be considered as a third country and there will be restrictions on data flows,” said Elizabeth Denham, U.K. Information Commissioner, at the 40th International Conference of Data Protection and Privacy Commissioners in October.

Neil Hodge is a freelance business journalist and photographer based in Nottingham, United Kingdom. He writes on insurance and risk management, corporate governance, internal audit, compliance, and legal...