Westminster Bridge was placed on lockdown after police discovered a suspicious package.
Bomb disposal squads carried out a "controlled explosion" on the busy bridge after the alarm was raised at around 7.30am on Thursday.
The Met confirmed it received reports of the suspicious item and immediately deployed army disposal units to the scene.
Traffic ground to a halt as officers cordoned off an area between Jewel Tower and Millbank House. Passersby were quickly evacuated from the surrounding streets.
Members of the public were allowed back into College Green park at around 8.15am—almost an hour after the alert was raised.
Following the controlled explosion, the package was found to be non-threatening.
Sky News reported the package had contained Christmas cards from a Labour minister.
Last month, bomb disposal teams were called to Stockport railway station after a suspicious suitcase was discovered on a footbridge.
Police, fire crews and paramedics rushed to the scene before establishing a 200-metre cordon, causing travel chaos across the network.
The station was completely evacuated with all trains in and out cancelled following the scare. Explosive Ordnance Disposal units raced to Greek Street as nearby homes were also reportedly evacuated.
