A MAN has been arrested for carrying a medieval sword in Adelaide city.

A Public Transport Safety Branch police patrol spotted a man walking along Bank St carrying a large sword just before 11.30am on Sunday.

The patrol approached the armed man, who had nearly reached North Tce, before arresting him and seizing the 1m medieval metal sword.

A Wynn Vale man, 38, was charged with carrying an offensive weapon and breaching his bail.

Police are investigating why he was carrying the large sword.

The arrested man is expected to be refused police bail and appear in the Adelaide Magistrates Court on Monday.