The relics, packed in tiny bundles of cloth including one scrap of fabric more than 1000 years old, were found when a 12th century German portable altar was opened for the first time since it came into the British Museum collection in 1902.

It was in for a condition check and cleaning, before going on display in the gallery, which opens today. But to the amazement of James Robinson, curator of medieval antiquities, when it was opened a linen cloth was revealed, and inside it dozens of tiny bundles of cloth, each neatly labelled on little pieces of vellum.

The most precious was the relic of St Benedict, an Italian who in the early 6th century was credited as the father of the western monastic tradition, founding monasteries and establishing guiding principles still followed at many monasteries. The relic was wrapped in cloth which was itself an extraordinary object, a piece of silk from 8th or 9th century Byzantium.

Each Catholic altar-stone is supposed to contain at least one relic of a saint, usually in the form of minute flakes of bone. There was a clue on the back of the museum's altar in a list of names beginning slightly implausibly with John the Baptist, and including saints James, John and Mary Magdalene.

There are many reliquaries in the gallery, in the form of crosses, pendants and rings, including one owned by a saint, the Georgian queen Kethevan who was executed by Shah Abbas in 1624 for refusing to convert to Islam. The newly discovered saints will remain at the museum.

Guardian News & Media