The Met Police says that a firearm has been seized and two men arrested after armed officers stopped a minicab in Southwark Park Road on Tuesday.
Two men, who were passengers in the vehicle, were detained and a revolver wrapped in a bandana was recovered.
The firearm was made safe and has been sent off for testing.
Both men, aged 22 and 18, were arrested on suspicion of possession of a firearm with intent to endanger life. They have been taken to a south London police station where they remain in custody.
The investigation is being led by officers from the Met’s Specialist Crime Command.
Detective Constable Rob Smith, the investigating officer, said: “As a result of this investigation, a dangerous weapon has been taken off the streets. This weapon could have easily gone on to seriously injure, or even kill, somebody.
“Firearms have absolutely no place on our streets and their removal makes London a safer place for all.
“I want the public to be reassured that even during these challenging times, the Met remains committed to tackling violent crime and seizing weapons such as this one. We will continue to crackdown on criminals and bring them to justice.”