The closure is due to the discovery of defective steelwork within the structure.
Work is already underway to repair the FRB.
However, following a meeting of the Scottish Government Resilience Committee (SgoRR), the decision was made to close the bridge following inspections carried out by specialist engineers.
Transport Minister Derek Mackay said: "The decision to close the Forth Road Bridge is not taken lightly. It is based on the expert opinion of the engineers who operate the bridge day to day and that of independent experts in the field.
"Every effort is being made to open the bridge as quickly as possible but safety is the main priority, however these works are weather dependent given the height and location of the bridge. We are aware of the potential economic impact, for strategic traffic in the east of Scotland and on people living in local communities.
-- Advertisement --
"This is an unprecedented challenge in the maintenance of the Forth Road Bridge. On balance, following advice from engineers and independent experts, the full closure is essential for the safety of the travelling public and to prevent further damage to the structure of the bridge.
"The bridge operators Amey have a robust inspection team in place and these defects are problems that have only occurred in the last number of weeks.
"We are taking every step we can to lessen the impact of this closure.
Mark Arndt, Amey's Account Director responsible for the bridge, said: "This is a complex engineering challenge. The component failure is in a difficult to access location and our response is also highly dependent on weather conditions.
"We continue to work around the clock on inspections, assessments and calculations along with the development of designs to effect the necessary repairs, while at the same time mobilising all the resources required to reopen the bridge as soon as is possible."
(LM/CD)
