A former Nigeria oil minister and three election officials have been charged with money-laundering. Ex-minister Diezani Alison-Madueke was accused of bribing the officials before the 2015 presidential election that saw President Muhammadu Buhari emerging as winner.
The bribes amounted to almost N265m ( £694,493; $866,865), according to the Premium Times newspaper.
The three officials appeared at the Federal High Court in Lagos on 5 April. One pleased guilty and the other two not guilty.
Madueke was not in court and a charge sheet described her as being "still at large."
Madueke served under President Goodluck Jonathan, who lost to Buhari in 2015. She was arrested in London in 2015 on suspicion of bribery and money laundering, charges she has always denied.
More on Alison-Madueke and corruption in Nigeria
Alison-Madueke, who became the first female president of the Organization of the Petroleum Exporting Countries (Opec) in 2014, was arrested days after Nigeria's President Muhammadu Buhari appointed himself as the country's oil minister, after he vowed he would recover millions of dollars worth of funds he alleged were stolen during previous administrations.
The leader also alleged some 250,000 barrels of Nigerian crude oil are stolen every day and sold to other countries at higher prices. In order to stop illicit activities in the oil industry, Buhari replaced the whole board of the state-run Nigerian National Petroleum Corporation (NNPC) and temporarily banned some 113 vessels from taking crude oil from Nigerian ports.
While Alison-Madueke was in office, former governor of Nigeria Central Bank Sanusi Lamido Sanusi was suspended after he claimed $20bn (£12bn) of oil revenue "went missing" from state oil company Nigerian National Petroleum Corporation (NNPC).
According to the Premium Times, Alison-Madueke – who has been dubbed "one of the most powerful officials of President Goodluck Jonathan" – admitted to spending $3.5bn (£2.3bn) of Nigeria's money without budgetary approval in February 2014.
During her time in the role, she supported the unpopular attempt by Jonathan in 2012 to end fuel subsidies, arguing it posed a financial burden on the government's finances. The government backtracked on its decision following rallies that caused at least 16 deaths.