British researchers say new technology can read "unreadable," fragile historic documents that could crack and crumble if unrolled or unfolded.

Pioneering X-ray technology developed at Cardiff University and Queen Mary, University of London is making it possible to read such historical documents for the first time in centuries, they said.

The research was funded by Britain's Engineering and Physical Sciences Research Council, which said the breakthrough means historians will be able to access previously unusable written sources and gain new historical insights.

The new technology enabling parchments to be unrolled or unfolded "virtually" and the contents displayed on a computer screen, a council release reported Thursday.

It works by scanning a parchment with X-rays to detect the presence of iron contained in "iron gall ink," the most commonly used ink in Europe from the 12th to the 19th centuries.

A three-dimensional "map" showing the ink's exact location is built up from a series of X-ray "slices" taken through the parchment.

Software then combines the data obtained with information about the way the parchment is rolled or folded to produce an image of the document as it would appear flat.

"This is a milestone in historical information recovery," Cardiff researcher Tim Wess said. "The conservation community is rightly very protective of old documents and isn't prepared to risk damaging them by opening them.

"Our breakthrough means they won't have to."