British police said an unattended item found in central London had been determined not to be suspicious and a number of roads which were closed as a precaution would now be reopened.
Police earlier closed bridges, covering a roughly one mile stretch of the River Thames while they assessed the item.
"The unattended item has been assessed and was found not to be suspicious. Road closures will be lifted imminently," police said on Twitter. Trains to several stations were temporarily disrupted while the security alert was dealt with.
Britain last week lowered its national terrorism threat level from severe to substantial, meaning an attack was considered likely rather than highly likely.
(Reporting by Kate Holton, writing by William James and Kylie MacLellan)
