It's a cover-up: New Bansky artwork hidden by guards at London's Royal Courts of Justice

British police have moved quickly to cover-up a mural painted by the legendary artist Banksy on a wall of London's Royal Courts of Justice.

The artwork shows a wig and gown wearing judge using a gavel to hit a protester lying on the ground while holding what appears to be a blood-splattered placard.

It's believed to be a reference to recent pro-Palestinian demonstrations in the UK capital and beyond that have led to hundreds of arrests.

Banksy confirmed the mural on the Queen's Building at the complex was his by posting a picture of the work on Instagram on Monday.

The artwork has now been concealed by metal barriers and is being monitored by security officials.

Banksy, who's real identity remains unknown, often comments on cultural, social and political issues with thought-provoking and satirical stencilled street art and graffiti.

Earlier this year, he posted a picture of a lighthouse in the southern French Mediterranean city of Marseille which was quickly vandalised after its location was confirmed.

He also made worldwide headlines last summer when he posted a surprise series of animal-themed artworks across London over several days in a bid to "lift the public's spirit".