IT looks like nothing more than an old rock. Standing alone near the end of the runway at Edinburgh Airport, the Cat Stane barely warrants a second glance from the few people that ever walk past it. But the remains of what appears to be a Latin inscription, just visible beneath the moss, offer a tantalising clue to the flurry of interest it has generated.

The rough rock, which stands 4ft high, dates back more than a thousand years - and may be the final resting place of an ancient tribal princess, Vetta.

Vetta is thought to have been an important woman among the Votadini, a British tribe who inhabited West Lothian. Their language and customs were closely related to the Welsh tribes, who lived around 1500 years ago.

The ancient stone marks a burial site which is set to be excavated as part of the £500 million project to build a rail link to the airport.

The railway tunnel which would be built as part of the link would pass through the edges of the burial ground.

Archaeologists - who fear work on the site could destroy some of the remains - have been given permission to excavate the site before the mechanical diggers move in.

As part of the work, it is thought the rock itself is likely to be removed and put on display to the public, possibly at one of Edinburgh's museums.

The land around the rock is believed to have been used as a burial ground for thousands of years from the earliest times people lived in the area.

Archaeologists hope the opportunity to explore the site will offer a fascinating insight into the Capital's ancient history.

The burial ground was excavated around 30 years ago, but it is thought modern technology will allow far more evidence to be unearthed.

Transport Initiatives Edinburgh (TIE) - the council-owned company behind the airport rail link plans - has agreed to the excavation going ahead before any work starts on the tunnel.

Work on the rail link is expected to start early next year, provided the project receives the backing of MSPs later this year.

Susan Clark, project director for the Edinburgh Airport Rail Link (EARL) project, said: "Agreement has been reached with Historic Scotland to carry out whatever excavation of the Cat Stane is deemed necessary.

"TIE has worked closely with Historic Scotland to ensure that the Cat Stane is treated appropriately and that the archaeological work can be conducted.

"The construction work for EARL has necessitated the excavation of the Cat Stane, which has long been inaccessible to archaeologists as it has been part of the airport. My team and I are delighted to be able to help in the excavation of this valuable piece of local history, and we look forward to seeing what Historic Scotland unearths in its work."

On the south bank of the River Almond, the small stone memorial, is the only visible element of the ancient burial site. There has been no public access to the rock for years, because it lies within the airport boundary.

A Historic Scotland spokeswoman said: "We have worked closely with TIE to identify the best solution to securing the future conservation and investigation of the Cat Stane and associated long cists which all lie within the scheduled area."