Nigeria's government spent 80% of its revenue on debt servicing last year, a ratio that could rise to around 100%, the International Monetary Fund estimates.

"Eighty percent is not sustainable and our plan is that it is coming down to 60% in 2023," Zainab Ahmed said in a Bloomberg TV interview, adding that the country expected to produce 1.6 million barrels of oil a day this year.

(Reporting by Marc Jones, Editing by Rachel Savage)