Three raids, involving some 30 officers in the town of Dartford, were carried out in tandem with similar operations by US authorities in New Jersey, officials said.

The raids were part of Operation Trident, which for several years has targetted the arms trade linked to drug trafficking in black communities in the British capital.

A 55-year-old man was in custody, the spokesman said.

"This is the biggest firearms haul we have ever had," Detective Superintendent Kevin Davis.

"The premises raided were used to store hundreds and hundreds of weapons. I have never seen anything like it," he said.

"Guns are mounted on every available wall space in the property and live ammunition was found lying on the floor.

"There are guns everywhere. It will take us at least three days to log it all and bag up the evidence."