President Koroma has been under house arrest since the attack last November
Former Sierra Leone President Ernest Bai Koroma has been charged with four counts of treason in connection with an attempted coup.
Last November, gunmen broke into a military armoury and several prisons in Freetown, freeing almost 2,000 inmates.
He has previously denied any involvement in the attack.
West African leaders are trying to broker a deal for Mr Koroma to move to Nigeria in return for the charges being dropped, the BBC understands.
The BBC has seen a letter saying Mr. Koroma has agreed to the deal, brokered by the regional group, Ecowas, however he has not commented publicly.
He will travel to Nigeria on Thursday, subject to the approval of Sierra Leone's President Julius Maada Bio, the letter says.
Some of Mr Koroma's supporters cried in court as the charges were read out, according to the Reuters news agency.
On Tuesday, 12 other people were charged over the attempted coup, including one of Mr Koroma's former bodyguards.
