Militant attacks on oil installations and a threatened nationwide strike are driving Nigeria's petroleum production and its naira currency to new lows.

Angola has become Africa's biggest oil producer as Nigeria's output slumped to 1.4 million barrels a day, the oil minister reported, endangering a budget based on production of 2.2 million barrels. The naira fell to 350 to the dollar on the parallel market, against an official rate of 199.

Two leading labor unions with millions of members called for a strike Wednesday to protest a 70 percent increase in gasoline prices, forced by a lack of foreign currency.

The crisis is dividing labor leaders on religious and ethnic lines, with those from the Muslim north against the strike and Christians from the south urging citizens to "Occupy Nigeria!"