A local inquiry into the Hindhead tunnel finished in 2005

The existing A3 road would be diverted into the proposed 1.9km (1.2-mile) tunnel under the Devil's Punch Bowl at Hindhead in a bid to ease bottlenecks.

However, final approval will only be made once consultation into the increased �370.9m cost is completed.

Campaigners are calling for assurances that the existing A3 will stay open.

The Save The Old A3 group is in favour of the tunnel being built but is worried that, if the old road was closed and the tunnel was ever shut, traffic would be diverted through nearby villages.

'Important scheme'

Under the plan the old section of road across Hindhead Common would be "detrunked", meaning it became the responsibility of Surrey County Council.

A local inquiry into the plan was held between September 2004 and February 2005 and the government has since approved funding for the tunnel scheme after advice from the South East England Regional Assembly.

Roads Minister Stephen Ladyman said: "This is an important scheme, but before taking a final decision it is clearly right to give people who provided evidence at the inquiry a chance to comment given the estimated increase in scheme costs."

The estimated cost when the original inquiry began in September 2004 was �270m.