Bangs were heard outside BBC headquarters after police were called to a report of a suspicious vehicle.
Officers were called to Portland Place at 3.15pm on Monday and some of the corporation’s employees said a number of controlled explosions were carried out.
An area around the well-known building in central London was cordoned off and images shared on Twitter showed what appeared to be a police robot being used on an orange van.
Journalist Manuela Saragosa tweeted: “We’re still in lockdown at BBC New Broadcasting House. No-one allowed in or out of building.
“There’ve been two controlled explosions so far, a bomb robot is at work and all surrounding streets cordoned off … want to go home!
The Metropolitan Police would not confirm any controlled explosions but said the incident had been stood down some three hours after they were first called.
The force said: “We were called at 3.15pm to a report of a suspect vehicle on Portland Place, Westminster.
“The incident has now been stood down and police cordons are being removed. Thanks for your patience as officers worked at the location.”
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