A former Nigerian oil minister and three election officials have been charged with money-laundering.
The ex-minister, Diezani Alison-Madueke, has been accused of bribing the officials before the 2015 elections. She was not present to enter a plea, and was described on the charge sheet as being at large.
In the past she has rejected accusations that she was corrupt.
Ms Alison-Madueke served under President Goodluck Jonathan. He lost the election to Muhamadu Buhari.
The Economic and Financial Crimes Commission says one of the three officials pleaded guilty, and the other two not guilty.