The ceremonial mace of Nigeria's upper chamber of parliament was stolen on Wednesday, Senate leaders said, condemning the theft as an "act of treason"."Today, some hoodlums... seized the symbol of authority of the Upper Legislative Chamber, the mace," said Senate media and public affairs chairperson Aliyu Sabi Abdullahi in a statement."This action is an act of treason, as it is an attempt to overthrow a branch of the federal government of Nigeria by force and it must be treated as such," he added.Parliament cannot convene without the mace, a metre-long metal rod traditionally carried by the Senate speaker upon entering and leaving the chamber.Media reports from Nigeria's parliament said there were scuffles as the mace was taken out of the chamber and the parliament building. It was then put into a black all-terrain vehicle, which drove off.The Senate statement, which said the action was an "affront to the legislature", accused a suspended senator of leading the thieves.Seizing the mace has been a long-established tactic to express discontent with parliamentary proceedings in the Senate and the lower House of Representatives, as well as state legislatures.In 2000, the then-Senate president himself allegedly removed the mace from the chamber and took it to his hometown in a dispute with his deputy over the resumption date after recess.Chuba Okadigbo vowed there was "no way" he would surrender it. A new one was later made and parliament was reconvened.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTER FOLLOW News24 Africa on Twitter and Facebook.