A man has been arrested outside Buckingham Palace after he threw shotgun cartridges on the royal residence grounds.

The serious security incident which occurred just days from King Charles’ coronation forced the palace into a lockdown this morning.

Met Police said officers had quickly detained him at around 6am NZT after he approached the gates of Buckingham Palace, SW1 and threw a number of items - suspected to be shotgun cartridges - into the Palace grounds.

“These have been recovered and will be taken for specialist examination,” a Met Police spokesperson said.

The man had been arrested on suspicion of possession of an offensive weapon and cordons remain in place after he was also found to be in possession of a suspicious bag, they said.

“Specialists attended and following an assessment a controlled explosion was conducted as a precaution.”

Chief Superintendent Joseph McDonald said officers worked immediately to detain the man and he had been taken into police custody.

“There have been no reports of any shots fired, or any injuries to officers or members of the public.

“Officers remain at the scene and further inquiries are ongoing.”

Witnesses told Daily Mail UK the man was seen throwing a “number of items” on the residence grounds.