LONDON (AP) — Britain’s postal service said it was hit Wednesday by a “cyber incident” that is temporarily preventing it from sending letters or parcels to other countries.

Royal Mail reported on its website that international export services were “experiencing severe service disruption” without providing further details.

“We are temporarily unable to dispatch items to overseas destinations,” the service said, adding that it recommended customers hold on to mail destined for outside the country while it works on fixing the problem.

“Some customers may experience delay or disruption to items already shipped for export,” Royal Mail said.

The British government’s National Cyber Security Center said it’s aware of the incident and is working with Royal Mail and the National Crime Agency “to fully understand the impact.”

Services for mail coming into the country are operating with minor delays, Royal Mail said.