For the handful of hardy travellers who make it to the Abuna Garima monastery in Ethiopia's Tigray Highlands, there is a book that local monks believe holds magic properties.

Kept under lock and key in a bright-blue circular hut at the centre of the isolated monastery, the Garima Gospels are one of the Christian world's oldest and most exquisite treasures.

Until recently, scholars had always assumed that the two 25cm-thick volumes, which are written on goat skin and brightly illustrated, dated back to the early 11th century. But recent carbon-testing has proved what the monks believed all along: the books are among the oldest gospels in existence.

New dating techniques have put the creation of the two books to somewhere between AD330 and AD650, making them a close contender to being the most ancient complete Christian texts.

The only major collection of scripture that is known to be older is the Codex Sinaiticus, a copy of the Bible hand-written in Greek which dates back to the third century. Unlike the Garima Gospels, the Codex includes large chunks of the Old Testament, but the entire work is divided between museums and monasteries in Egypt, Britain, Russia and the US. The Garima Gospels, meanwhile, have been in one piece in the same place for the best part of 1600 years, guarded by generations of monks from Muslim invaders, colonial conquerors and a fire in the 1930s which destroyed their church.

The Ethiopian Heritage Fund, a British charity which specialises in preserving the artefacts that fill Ethiopia's monasteries, has finished restoring the two books.

Reaching the monastery, which is 2130m above sea level and clings to a mountainside, was no mean task. Lester Capon, a British bookbinder, spent three weeks rebuilding and restoring the bindings that held the pages together.

An earlier conservation project in the early 1960s had resulted in some sections of the gospels being sewn together entirely. Capon had to undo the stitches, take out each page, clean it and put it back in the right order. Jacques Mercier, a French expert on Ethiopian manuscripts, was on hand to ensure each page was put back correctly.

- Independent