Armed police stormed a double-decker bus following reports of a passenger holding a gun to discover it was only a cigarette lighter.
A panicked passenger dialled 999 just before noon yesterday when they thought they had spotted the weapon.
Scores of officers armed with guns arrived and stopped the bus in the centre of Thornton Heath, south London.
But when police searched the man they found no weapon, and it is now believed that a cigarette lighter was mistaken for a gun.
A Met Police spokesman said officers were called when the number 60 bus that was travelling from Streatham to Old Coulsdon.
He said: “We were called at 11.45am to reports of a passenger on a bus in Croydon holding a firearm.
“Armed officers stopped the bus in central Croydon and searched the man but he was not in possession of a firearm.”
The raid comes at a time when police are on heightened alert for a “Mumbai-style” terror attack, after Home Secretary Theresa May warned that the threat level is now ”more dangerous than at any time before or since 9/11”.
In a further sign of increased tensions, Holbon station was evacuated following a security alert at just after 6pm last night.
Armed officers from British Transport Police and the Met filed sealed off the station after a commuter reported a passenger carrying a suspected firearm.
The incident caused severe delays for commuters on the Piccadilly Line but after searching the platforms nothing suspicious was found and the station reopened 45 minutes later.
A BTP spokesman said: “We were called to reports of someone having seen a passenger with a firearm. We attended with officers from the Metropolitan Police but nothing suspicious was found.”
Nick Edmonson tweeted: “Delayed journey home due to huge police presence at Holborn station. I’ve decided that seeing armed police does not make me feel safer.”
