A man has been arrested after climbing over Buckingham Palace's front gates in the middle of the night, police have said.
The 22-year-old was held on suspicion of trespass at around 02:00 BST on Wednesday by specialist royal officers, the Metropolitan Police Service said.
The Queen was in residence at the time, a palace spokeswoman confirmed.
The intruder was not carrying a weapon and the incident is not being treated as terror-related, the force said.
The palace spokeswoman declined to say whether the Queen had been informed of the incident.
At their lowest point the gates are several metres high.
The man has been released under investigation, Scotland Yard said.