Waterloo Bridge, Westminster Bridge and part of Victoria embankment have been cordoned off by police after reports a Second World War bomb had been dredged up in the Thames.
The device was found in the river by Victoria Embankment. Westminster Police said in a tweet: "Please bear with us as we deal with dredged up suspected WWII ordnance."
A spokesman for the Met Police said: "There are road closures in place in and around the area whilst the item is assessed."
The closure is causing extensive travel disruption, with a large police presence at the scene.
Many commuters took to social media to voice their frustration at the hold-up during rush hour.
MBNA Thames Clippers tweeted: "The river is closed between Charing Cross bridge and Westminster bridge, this is expected to be closed overnight."
Transport for London confirmed Waterloo Bridge had reopened in a southbound direction, however it was still closed northbound. Both Westminster Bridge and Victoria Embankment remain closed.
