Soaring costs threaten 1.3-mile tunnel under world heritage site.

Government plans to build a 1.3-mile tunnel under Stonehenge were put on ice yesterday as the cost of the proposed scheme spiralled to £470m. The tunnel, which was planned as a measure to ease congestion on the A303, was costed at £284m in 2003. Now roads minister Stephen Ladyman, says there will be a “detailed review" of the options because of the "very substantial" increase.

The Highways Agency said that its estimate of the increase in cost was due to the large quantities of soft chalk in the area, and the high water table, which would make the construction of the tunnel more complicated that originally thought.

Mr Ladyman said: "Our recognition of the importance of Stonehenge as a World Heritage Site remains unchanged but given the scale of the cost increase we have to re-examine whether the scheme still represents value for money and if it remains the best option for delivering the desired improvements.”

The Campaign to Protect Rural England criticised the government’s decision, fearing that the review would “mean cost-cutting measures threatening the most environmentally sensitive option for this site of international importance.”