Nigeria's government revenues fell in January to 370.388 billion naira ($1.86 billion), down from 387.777 billion naira in December, due to a drop in oil prices, the finance minister said on Tuesday.

"There was a slight increase in production of crude in December 2015 but the resulting income was marginal due to a 10 percent drop in crude oil prices," Finance Minister Kemi Adeosun said in a statement.

"Shut-in and shut-down of operation for repairs and maintenance continued during the period under review," she added.

The revenue includes VAT, refunds from state oil firm NNPC and exchange gains, the statement said. It will be distributed to the federal, state and local authorities.

Adeosun also said that the rainy day fund, the Excess Crude Account, remained unchanged at $2.26 billion.

Nigeria, Africa's top oil producer and biggest economy, relies on crude sales for about 70 percent of its government revenues. Global crude prices have fallen sharply since mid-2014, hurting the country's public funds and leaving many states unable to pay public salaries in time or fund infrastructure projects and other state services.

($1 = 198.6000 naira)