Stonehenge has been put forward as an addition to “the World Heritage in Danger” list by the United Nations Educational, Scientific and Cultural Organisation (Unesco).

The UN organisation’s World Heritage Committee has published a draft decision to add the ancient monument in Wiltshire to the list, which aims to support conservation action and international assistance on threatened sites.

It comes amid ongoing concerns and lengthy legal battles over plans to build a nearby road tunnel to ease pressure on the A303.

Save Stonehenge World Heritage Site (SSWHS) lost a High Court challenge in February over Transport Secretary Mark Harper’s backing of plans, which include the two-mile tunnel, to overhaul eight miles of the road.

Easter getaway
Cars make their way along the A303 past Stonehenge in Wiltshire (Andrew Matthews/PA)

The UN draft document notes: “The proposed A303 Scheme remains a threat to the Outstanding Universal Value (OUV) of the property.”

The World Heritage Committee (WHC) will vote on adding the site to the danger list at a meeting in New Delhi between July 21 and 31.

National Highways said the plan for the tunnel would remove the sight and sound of traffic passing the site and cut journey times.

However, the Stonehenge Alliance, which is campaigning against the tunnel, has welcomed the committee’s proposals.

Historian Tom Holland, the group’s president, said: “When in a hole, stop digging – and when the hole is one that has been dug by your political opponents, definitely stop digging.

“The new government will have the perfect opportunity to reverse a road scheme that is not only ludicrously expensive but risks huge damage to the country’s international reputation.

“We hope that whoever comes to power next week will seize it.”

Bank Holiday getaway
The tunnel plan is in response to building traffic on the A303, which is a congestion hotspot, with drivers heading to and from the South West often stuck in long queues (Andrew Matthews/PA)

John Adams, a SSWHS director, said: “This is a damming verdict on National Highways’ plans.

“Whichever way you look at it, this scheme will be hugely damaging and should be scrapped.

“The money should be spent instead on improving public transport links to and around the South West.

“That would be the best way of reducing pressure on the A303, while still retaining the view of the Stones for passing travellers.”

The Stonehenge site, 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 A303 is a congestion hotspot, with drivers heading to and from the South West during peak holiday periods often stuck in long queues on the single-carriageway stretch near the stones.