Climate Activists have closed Bank Junction, forcing 17 bus routes on to diverted routes.
Hundreds of Extinction Rebellion activists set up camp in the junction to "block routes that financial district workers take to work".
Since 21 May 2017 only buses and cyclists have been allowed to use Bank junction on weekdays from 07:00 to 19:00.
In a statement the group said the action was to "highlight the far greater disruption faced by those living in the environments systematically being destroyed by UK backed companies".
City of London Police said a "policing plan" is in place "which will be proactive in ensuring any impact on our communities is minimised as much as possible".