City of London Police attended a building in St Martin's Le Grand, near St Paul's, after reports of a suspicious package earlier - but the package has now been deemed non-suspicious.
City streets were closed earlier, as police advised people to avoid the surrounding area. Some shops and businesses in the surrounding area were evacuated, according to reports.
However, the police said: "The item has now been deemed non suspicious and officers are working to clear the incident. Cordons are still currently in place."
St Paul's station was closed due to the investigation, but has now reopened.
The entire length of St Martin's Le Grand was closed, from London Wall to Cheapside, as well as Newgate Street, between Old Bailey and Cheapside, but have started to reopen as the security alert comes to an end.
Twitter users posted photos of the scene: