A monumental Bible rumoured to have been written with the help of the Devil has been returned to Prague for the first time in 350 years.

	An illustrated page of the 'Codex Gigas' also known as 'Giant Book' and 'Devil's Bible'

The 13th century Codex Gigas, which is 3ft long and weighs 165lb, is thought to be the biggest book in the world and is known as The Devil's Bible due to a supposed satanic bargain made by its author.

It was looted by Swedish soldiers from Prague castle at the end of the Thirty Years War in 1648 and taken to Stockholm, where it is the prize exhibit at the Royal Library.

But until now Swedish authorities have refused to lend it to the Czech Republic, which regards the Bible as stolen property, for fear they would not get it back.

The priceless manuscript is housed in a vault-like room behind bullet-proof glass.

One of the two pages on show features a drawing of the Devil. According to legend, the drawing is the scribe's tribute to the role Satan played in the Bible's creation.

Sentenced to be walled up and die a slow death for some unutterable sin, a monk promised to write out the world's biggest Bible in return for his freedom. With just one night to produce it, he enlisted the help of the Devil.

The text will return to Sweden early next year.

According to legend the scribe was a monk who breached his monastic code and was sentenced to be walled up alive. In order to forbear this harsh penalty he promised to create in one single night a book to glorify the monastery forever, including all human knowledge. Near midnight he became sure that he could not complete this task alone, so he sold his soul to the devil for help. The devil completed the manuscript and the monk added the devil's picture out of gratitude for his aid.

Despite this legend the codex was not forbidden by the inquisition and was studied by many scholars.

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The priceless piece, considered the biggest medieval book, was taken from the Prague Castle by Swedish troops at the end of the Thirty Years' War in 1648. It is in Prague on loan from Sweden's Royal Library in Stockholm. It was put on display under high security at the Czech National Library.

It contains "a sum of the Benedictine order's knowledge" of the time, including the Old and New Testament, "The War of the Jews" by the first-century historian Josephus Flavius, a list of saints, or a guideline how to determine the date of Easter, Uhlir said.

"I would estimate it took him between 10 and 12 years to write," he said about the piece, which weighs 75 kilograms (165 pounds). Originally, it had 640 pages, of which 624 survived in relatively good condition, he said.