Parliament was hit by a major security breach after an intruder jumped a barrier to gain access to the estate on Wednesday afternoon.
Armed police officers chased down the male suspect and wrestled him to the ground inside New Palace Yard before leading him away.
Officers bundled the man into the back of an arriving police van while he shouted “my rights” and “I need a lawyer”.
One officer told The Independent the man accessed the yard by “jumping” a security barrier at the Carriage Gate entrance used by Boris Johnson and other ministers.
The same entrance was where PC Keith Palmer was killed in a knife attack in 2017 while guarding the parliamentary estate.
The Metropolitan Police alter said the man had been arrested on suspicion of “trespassing” on a protected site.
A spokesperson said: “At around 3pm on Wednesday, 1 December, a man was detained and arrested at Carriage Gates inside the Palace of Westminster on suspicion of trespassing on a protected site.”
Scotland Yard said the arrest is not terror related, and enquiries are being made into the circumstances of the security breach.
The main gates were briefly put into lockdown during the security scare on Wednesday afternoon.
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