Campaigners have won a court battle over British transport minister Grant Shapps' decision to approve a controversial road project which includes a tunnel near Stonehenge.

Save Stonehenge World Heritage Site (SSWHS) challenged his decision to back the £1.7 billion scheme to overhaul a section of the A303, including the 3.2km tunnel.

The go-ahead was given in November last year, despite advice from Planning Inspectorate officials that it would cause "permanent, irreversible harm" to the Unesco World Heritage Site in Wiltshire.

In a ruling, Mr Justice Holgate found the decision was "unlawful" on two grounds.

He concluded that there was a "material error of law" in the decision-making process because there was no evidence of the impact on each individual asset at the historic site.

He also found that Mr Shapps failed to consider alternative schemes, in accordance with the World Heritage Convention and common law.

Rowan Smith, a Leigh Day solicitor who represented the campaigners, said: "This is a huge victory, which means, for now, Stonehenge is safe.

"The judgment is a clear vindication of our client's tremendous efforts in campaigning to protect the World Heritage Site.

"The development consent for this damaging tunnel has been declared unlawful and is now quashed, and the Government will have to go back to the drawing board before a new decision can be made.

"Meanwhile, one of the country's most cherished heritage assets cannot be harmed."

A panel of expert inspectors recommended that development consent should be withheld because the project would substantially and permanently harm the integrity and authenticity of the site, which includes the stone circle and the wider archaeology-rich landscape.

In a report to Mr Shapps, the officials said permanent, irreversible harm, critical to the outstanding universal value of the site, or why it is internationally important, would occur, "affecting not only our own, but future generations".

The Stonehenge site, together with Avebury, was declared by Unesco to be a World Heritage Site of Outstanding Universal Value in 1986 on account of the size of the megaliths, the sophistication of their concentric plans and the complexes of Neolithic and Bronze Age sites and monuments.

The proposed tunnel is part of a £1.7 billion investment in the A303 between Amesbury and Berwick Down.

The road, which is a popular route for motorists travelling to and from the South West, is often severely congested on the single carriageway stretch near the stones.

Highways England says its plan for a tunnel will remove the sight and sound of traffic passing the site and cut journey times, but some environmentalists and archaeologists have voiced their opposition to the plan due to its potential impact on the area.

The project is classified as nationally significant, which means a development consent order is needed for it to go ahead.