Nigeria will start paying back a $5.1 billion debt owed to international oil companies, including Exxon Mobil Corp. and Royal Dutch Shell Plc, with a first installment this month in accordance with an agreement reached last year.

“The initial payments would be made by the end of April 2017,” Emmanuel Kachikwu, Nigeria’s Minister of State for Petroleum Resources, said in an emailed statement Wednesday. The energy companies are expected to reciprocate “by ensuring that they ramp up investments in the country’s oil and gas sector,” he said.

Nigeria reached the repayment deal in November with producers including Exxon, Shell, Chevron Corp., Total SA and Eni SpA that pump about 80 percent of the country’s crude in joint ventures with the state-owned Nigeria National Petroleum Corp. The debt, incurred from 2010 to 2015 due to Nigeria’s inability to make its share of capital contributions to the joint ventures, will be settled through crude sales over five years and will be interest-free, Kachikwu said at the time.

Settlement of the debt could unlock investments of as much as $15 billion by the international companies, Kachikwu said.