A volunteer police officer should be "struck off" after wrongly telling a Christian singer on London's Oxford Street that she was not allowed to sing church songs outside of church grounds.

Harmonie London, who posts videos of her Christian street performances on YouTube, was approached by the officer outside John Lewis department store as she sang worship songs to passers-by, reports GB News.

The officer told her, "No miss, you're not allowed to sing church songs outside of church grounds, by the way."

When Harmonie corrected her, the officer persisted and said she could not sing worship songs "outside of church grounds unless you have been authorised by the church to do these kind of songs".

The exchange between the officer and Harmonie was captured on video, with the recording uploaded to her YouTube channel.

The officer eventually walked away but not before sticking her tongue out to the camera.

Committed Christian and former Conservative minister Ann Widdecombe told GB News that the officer should be "struck off from the voluntary force".

She said there was "no basis" for what the officer had told Harmonie and that she had every right to sing Christian songs on the street.

"She really has got the law completely wrong and she was obviously enjoying herself rather too much, trying to boss this woman around," she said.

"And there is no basis at all for saying you can't sing. I could walk down the street singing Onward Christian Soldiers and I would be committing no offence at all."

Scotland Yard said it was "working to understand the context in which these comments were made".