The BBC’s Broadcasting House headquarters in London has been targeted and daubed in red paint.
Presenter Victoria Derbyshire posted images and footage of the scene showing the vandalised revolving glass doors and pale stone brickwork at Portland Place as she arrived for work on Saturday morning.
The BBC has faced criticism in recent days for maintaining its editorial stance not to describe Hamas militants as terrorists.
But the Metropolitan Police said the incident has not yet been linked to any protest group.
The piazza was closed off, with metal barriers in place behind yellow cleaning in progress warning signs.
Large brooms could be seen leaning against the glass doors, with the paint spread over the pavement.
Police officers stood guard outside, with an increased police presence in the capital where thousands of people are set to march in a pro-Palestinian demonstration on Saturday.
A Metropolitan Police spokesman said: “We are aware of criminal damage to a building in Portland Place, W1A.
“At this stage there is no suggestion this is linked to any protest group.”
BBC radio presenter and DJ Edward Adoo tweeted: “Just got to the BBC the main entrance is blocked someone sprayed red paint at the entrance.
“Regardless of your view on what’s going on this is not the way. Props to the security team on duty tonight.”
