Queen Elizabeth II has been overheard on video describing Chinese officials as "very rude to the ambassador" in a conversation with a senior police officer at a Buckingham Palace event celebrating her birthday.

The comments. which became public Wednesday, were unusual because the 90-year-old monarch has been careful to steer clear of politics during her long reign.

The discussion was recorded by a BBC cameraman. On the video, the police officer is describing the Chinese state visit to Britain in October.

The officer tells the queen it had been a "testing time."

Elizabeth then says: "They were very rude to the ambassador."

British officials have so far declined to comment on the queen's remarks.