Paul Flynn, the Labour MP for Newport West, has tabled a Commons motion calling for the Pennal Letter and Seal of Owain Glyndwr to be returned from France.

Mr Flynn says they are of great historical significance and should be reclaimed from the French National Library.

They should then be exhibited in Wales as tangible links between the Welsh Parliament of 1404 and the National Assembly of today.

Mystery still surrounds his burial place

The Pennal Letter was written by Owain Glyndwr calling for French support for his rebellion.

The letter was never answered, but remains in the French national archive.

At the same time, scientists are currently searching for Glyndwr's lost burial site.

The Scudamore family at Monington Court Farm at Golden Valley near Hay-on-Wye, have revealed the suspected grave of Glyndwr - a secret they have kept for centuries.

The land includes a historic Norman landmark and has long been listed as a site of special interest by English Heritage.

Centuries of speculation about the whereabouts of his body could be revealed by a geo-physical survey of the ground using hi-tech equipment.

'Fascinating'

Former professor of medieval archaeology Fred Talbot said the machinery would send a signal through the ground.

If the signal encounters a solid form, a high resistance is recorded and a low resistance is discovered if there is a hollow in the earth.

"The readout from the instruments creates a pattern by gridding the surface giving us a clear idea of what is below the surface," Mr Talbot explained.

Owain Glyndwr Society spokesman Tony Carter said the significance of the potential breakthrough had come at an interesting time.

"I think we need to know the facts," he said.

"We are on the threshold of the new Millennium, the 600th anniversary of Owain Glyndwr's rising and the first parliament at Machynlleth.