Carbon dating of fragments of the world's oldest known Quran, discovered in a British library, suggests it may be older than Muhammad, the founder of the Islamic faith, some researchers say.

Tests on the fragments found in Birmingham University Library put its age at between AD 568 and 645, those researchers say.

Since Islamic scholars believe Muhammad lived between AD 570 and 632, receiving the revelations that are the basis of the Quran between 610 and his death, the newly discovered fragments could predate the accepted founding date of Islam, some experts are saying.

"If we were to take the early dating [as fact] then it overthrows Islamic history as it is understood," says David Thomas, Birmingham professor of Islam and Christianity.

"It would mean that the Quran existed substantially as it has been passed down before Muhammad — before the traditional date of the beginnings of his revelations, or maybe even before he was born," he suggests.

Some scholars have suggested Muhammad, along with his first followers, took a text that already existed and altered it to reflect their own theological beliefs.

Thomas says it's possible but he doubts it, citing "a big problem" around the earliest date range ascribed to the document.

"As it turns out, on one of the four surfaces of our fragments we have a chapter division, which would seem to suggest that what we have was once a fully-formed Quran, possibly as early as the sixth century," he explains.

If it is in fact from the later part of the suggested date range, it would be evidence supporting "a traditional view" of Muhammad and the Quran, he says.

The fragments found in the Birmingham library, written on either goatskin or sheepskin, had mistakenly been bound into another copy of the Quran dating to the seventh century, part of a collection of around 3,000 Middle Eastern texts collected in Iraq in the 1920s.

There will likely be further tests, Thomas says, because a Quran confirmed as predating the Prophet Muhammad would set off "a radical revision of Islamic history.

"I think there are substantial obstacles in the way of that."

Officials at the Birmingham library said the manuscript would be put on display for the public for a month beginning in October.