An intruder has been detained and arrested inside the gates of Parliament after apparently managing to breach security.
The man was photographed pinned to the ground by armed police, while another officer pointed a gun at his head. He was later taken away in the back of a police van.
It is not yet clear how the man got inside but the incident will raise fresh concerns about security at the home of British democracy.
It is not being treated as terror related, the Metropolitan Police said.
Elliot Keck, who works in the office of Romford MP Andrew Rosindell, said it appeared that the man had climbed over the fence before he was tasered by police.
Mr Keck, 27, said: “As he was being tasered two armed police had their guns drawn.”
He added: “When it was established he wasn’t a threat armed police moved off and he was sat upright for a period before being taken to the van.”
Mr Keck said the man had discarded a bag which was also searched by police.
A statement from the Met Police said the man was "detained and arrested" Carriage Gates inside the Palace of Westminster at around 3pm.
He was arrested under suspicion of trespassing on a protected site," the force said, adding that "enquiries into the circumstances continue."
A House of Commons spokesperson said: “We are aware of an incident on the Parliamentary estate which is being attended by police and security staff.”
The incident comes just weeks after Tory MP Sir David Amess was killed after being stabbed while holding a constituency surgery in mid-October.