An unexpected message - in Chinese - has been broadcast over a public address system at a US National Weather Service office in Maryland.

It was also received on individual desk phones.

The US National Oceanic and Atmospheric Administration (NOAA) said it was a scam automated call, known as a robocall.

Reports of similar messages, delivered as audio recordings, have been made before.

"Our IT team in the building worked with the phone vendor immediately to prevent all outside telephone numbers from accessing the building's PA system, to prevent this from occurring again." said a spokeswoman for the US National Weather Service.

"At no point were NOAA's operations, data, or IT systems compromised by this robocall."

In April, the US Federal Trade Commission (FTC) warned the public about calls from scammers purporting to be from the Chinese consulate.

Recipients may be told they have a package to collect at the consulate, for example - this was the case with the message received at the weather office.

Chinese whispers
"If you get a call or message like this, hang up or delete it, and then tell the FTC," the commission advised.

A Weather Service employee, speaking anonymously to the Washington Post, said that the phone message arrived first, with the intercom message broadcast about 15 minutes later.

"We are aware of the Chinese message that is propagating through the phone system and was [broadcast] over the building [public address system]," said an email from an IT manager at the service, which was passed to the newspaper.

"The phone [system] is not tied to any of the government IT controlled systems in the building. Please do not be alarmed."