Nigeria's leading cellphone provider said Sunday it urgently needs diesel to prevent shutting down services countrywide, the latest business hit by a months-long fuel crisis in Africa's biggest oil producer. Many aircraft have been grounded with foreign airlines diverting to other African countries to fuel for flights abroad. Nigeria's woefully erratic electricity supply keeps businesses dependent on diesel generators. Nigeria produces more than 2 billion barrels of petroleum a day, but imports almost all refined fuel because its refineries aren't maintained.