Consumer inflation in Nigeria, Africa’s largest economy, rose to 9.0 percent year-on-year in May from 8.7 percent in April, the highest rate since May 2013, the National Bureau of Statistics (NBS) said.

Food Sub-Index rose to 9.8 percent year-on-year in May from 9.5 percent in April owing to late onset of rain which has pushed back the harvest season, as well as higher transportation costs due to scarcity of the Premium Motor Spirit (PMS) popularly called petrol in Nigeria.

“Food prices rose by 1.1 percent in May, the highest month-on-month increase recorded on food prices since September 2012,” the NBS said on Thursday.

Nigeria’s major cities still face gas shortages despite an end to the distribution strike which started the scarcity. But the country’s oil company has promised to release 1.1 billion litres of petrol to increase supply. The Nigerian National Petroleum Corporation (NNPC) also said that one of the country’s moribund refineries will resume production in August. The refinery located in Port Harcourt, a South-South city in Nigeria, will function at 80 percent of its installed capacity and produce five million litres of petrol per day.

However, with Nigeria’s daily petrol consumption currently at about 40 million litres, the resumption of production in Port Harcourt will not significantly reduce the country’s reliance on imports.

Oil marketers had stopped importation due to money owed them by the government. The dispute over subsidy payments almost shut Nigeria down in May.