Raids at three Havering industrial units led to cops seizing cannabis with an estimated street value of £300,000, along with a loaded AK47 assault rifle, a pistol, a converted revolver and two crossbows.
Police also found live ammunition, spent cartridges, cash, and Class B drugs during the intelligence-led operation in Rainham.
Detectives executed the search warrants on Monday - January 24 - and arrested a 62-year-old man at the scene on suspicion of drug supply.
He was taken to an east London police station and released on bail.
Det Sgt Owen Morgan said: “This successful operation, although led by the east area drugs focus desk, was the result of great collaborative team work across the borough, in particular by the violence suppression and gangs units.]
“The outcome is the disruption of organised crime that is a blight on communities.
“I have no doubt that the criminality we uncovered during the searches that spanned two days would have negatively impacted an area reaching far beyond Rainham and east area."
Anyone with information is asked to call police on 101, or to remain anonymous call the independent charity Crimestoppers on 0800 555 111.
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