A Christian manuscript dating back to the 3rd century has been sold for just over £3m after going under the hammer at London auction house, Christie's.

The Crosby-Schøyen Codex, believed to be Christianity's oldest surviving book and one of the oldest books in the world, was auctioned off in London on Tuesday, with bidding finally closing at £3,065,000.

The codex was one of the texts that formed part of the Bodmer Papyri, a collection of several texts discovered in the 1950s that included Christian writings, Biblical extracts, and pagan literature, and changed hands several times before being acquired by Dr Martin Schøyen in the 1980s.

Inscribed on papyrus by monks in an ancient Egyptian monastery, its remarkable preservation has been attributed to the region's arid climate. Its 104 pages, or 52 leaves, are now protected between double-sided plexiglass plates, and offer a unique window into the early life of the Christian faith.

The manuscript is written in Coptic, and its contents include the earliest complete versions of the First Epistle of Peter and the Book of Jonah ever found, as well as an Easter homily. Experts believe that it was written between 250 and 350 AD in one of the first Christian monasteries for use in liturgical services.

"The earliest monks in Upper Egypt in the earliest Christian monastery were using this very book to celebrate the earliest Easter celebrations, only a few hundred years after Christ and only a hundred or so years after the last Gospel was written," Eugenio Donadoni, Christie's senior specialist in books and manuscripts, told the BBC.

According to Mr Donadoni, the book possesses "monumental importance as a witness to the earliest spread of Christianity around the Mediterranean", and Christie's said Dr Schøyen, who started his collection of books as a teenager in the 1950s, deserved to be "remembered among the pantheon of great bibliophiles".

Around 60 lots from Dr Schøyen's collection were auctioned alongside the codex, with more than £7.5 million being raised by the sale of items including ancient legal texts, decorated religious manuscripts, and historical chronicles.