HAIFA — A sword believed to have belonged to a crusader knight about 900 years ago has been found by an amateur diver off Israel's northern coast.

The one-meter blade (3.3ft) blade was discovered by Shlomi Katzin and handed over to the authorities.

Shlomi Katzin was on one of his usual Saturday dives off the coast of Carmel beach, in northern Israel, when he stumbled across the discovery of a lifetime.

Recognizing that the sword is likely ancient and of great archaeological value, Katzin brought the artifact ashore and, fearing it may end up in the wrong hands, immediately contacted local authorities who handed over the item to the National Treasures Department.

It is thought the sword, which is encrusted with marine organisms, resurfaced after the shifting of sands.

The Israel Antiques Authority (IAA) said that once cleaned and analysed it would be put on public display.

"The sword, which has been preserved in perfect condition, is a beautiful and rare find and evidently belonged to a crusader knight," said IAA's Robbery Prevention Unit Inspector Nir Distelfeld.

"It is exciting to encounter such a personal object, taking you 900 years back in time to a different era, with knights, armour and swords."

Kobi Sharvit, who heads the IAA's Marine Archaeology Unit, said the Carmel coast, where the blade was found, provided shelter for ships during storms throughout centuries of shipping activity along the coast.

"These conditions have attracted merchant ships down the ages, leaving behind rich archaeological finds," he said.

Crusaders fought in a series of religious wars known as the Crusades, which were sanctioned by the Roman Catholic Church in the medieval period.

The most commonly known of the Crusades were campaigns in the eastern Mediterranean aimed at recovering the Holy Land from Muslim rule. — Agencies