A man has been arrested after climbing over the Buckingham Palace's front gates, the Met police said on Thursday.
The 22-year-old was held on suspicion of trespass at around 2 a.m. on Wednesday by specialist royal officers, the BBC quoted the Metropolitan Police Service as saying.
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 is presently in custody at a police station in central London.