The main index dropped to 43,260 points by 1122 GMT to a level last seen on Jan. 16.

Stocks, which have gained 16 percent so far in January, have been spooked by political standoff which could threaten the central bank's independence.

The central bank said on Monday it wouldn't hold a meeting to set interest rates due to its inability to form a quorum.

At the heart of the matter is a stalemate between the presidency and Senate over the latter's powers to confirm or deny executive nominees to government posts.

Traders had hinged this year's rally on hopes of a stable currency and lower interest rates driving corporate earnings.

The index of Nigeria's top 10 lenders fell 3.98 percent to lead the decliners.

Fidelity Bank, Diamond Bank, FCMB , Sterling Bank, Skye Bank and Union Bank shed more than 9 percent each to fall the most.