Officials said the crossing would be safe until at least 2014

A survey into corrosion of the support cables was carried out by the Forth Estuary Transport Authority (Feta).

The inspection predicted that by 2014 the bridge would be shut to heavy goods vehicles and by 2019 it would have to close to all traffic.

There were also proposals to charge �4 for cars crossing during rush hour.

However, there would also be a 50% reduction for cars with at least one passenger.

We are taking action now to prolong the life of the bridge Tom Aithcheson Feta chief executive

Feta recommended two new studies costing almost �3m to consider options for fixing the corrosion problem, including completely replacing or augmenting the main cables.

Chief executive Tom Aithcheson said: "The most important thing to get across is that the bridge is capable of carrying traffic now and for many years to come.

"We are taking action now to prolong the life of the bridge as long as possible."

'Trunk road' call

Acoustic monitoring will be introduced to scan the entire length of the cables.

The findings are to be discussed with representatives of the surrounding local authorities on 25 November.

John Mc Goldrick, of the National Alliance Against Tolls, repeated the call for the executive to take over the bridge and designate it as a trunk road.

"There has been a flurry of stories about the Forth road bridge, either saying that it will need to be replaced or that tolls will have to be increased to �4," he went on.

"The suggestion that the bridge must be replaced is premature. What is needed is more evidence from tests, followed by an independent assessment.

"The cost of building the bridge was paid off long ago. Under the present law, tolls should end next March."