Police cordons around Buckingham Palace are being lifted after a man was arrested for throwing what are believed to be shotgun cartridges onto the palace grounds.
A controlled explosion also took place involving the bag the man was carrying. Police said the controlled explosion was conduction as a precaution.
The man was arrested allegedly in possession of a weapon at about 7pm local time (4am AEST).
Police have taken the items the man threw onto the ground and will have them examined by specialists.
Police said the incident was not being treated as terrorism-related.
"Officers worked immediately to detain the man and he has been taken into police custody," Chief Superintendent Joseph McDonald said in a statement.
"There have been no reports of any shots fired, or any injuries to officers or members of the public."
Thousands of people were pushed back from the gates as police threw up cordons around the palace.
A crew from GB News was on the scene and was forced to evacuate the area as police set up the lockdown.
The King is currently in residence at the palace, where he met Prime Minister Anthony Albanese overnight, however, neither he nor Queen Consort Camilla were there at the time of the arrest.
Palace officials declined to comment, saying the incident was a police matter.
Security is expected to be heightened for Charles' upcoming coronation, set to be held in London on May 6.
Dozens of foreign royals, dignitaries and heads of state will travel to the UK to attend the event
On Saturday Charles and Camilla will ride in a gilded coach from the palace to Westminster Abbey, where they will be crowned in a ceremony steeped in history.
The pair will then return to the palace, escorted by a spectacular military procession featuring thousands of ceremonial troops, before they appear on the palace balcony to greet well-wishers.
Sign up here to receive our daily newsletters and breaking news alerts, sent straight to your inbox.
