Nigerian prosecutors on Thursday charged three senior military officers and a Lagos businessman with plotting to shoot down President Olusegun Obasanjo's helicopter and topple his government in a violent coup.
Appearing before the Federal High Court in Lagos, Major Hamza al-Mustapha, the former security chief to late dictator Sani Abacha, and three others pleaded not guilty to treason and to conspiring to remove Obasanjo from office.
All four were remanded in the custody of military intelligence.
Mustapha has been in custody since 1999 accused of the attempted murder of a newspaper proprietor who criticised Abacha's regime, but in March of this year he was removed from his civilian jail by military intelligence officers.
On Thursday, he was accused of having held secret meetings in Lagos's Kirikiri maximum security prison with serving military officers and with a hotelier, Onwuchekwa Okorie, and of plotting to overthrow the government.
Okorie was in court alongside Mustapha and Lieutenant Colonel Mohammed ibn Umar Adeka. The fourth defendant, navy Commander Yakubu Kudambo is on the run after escaping secret police custody. He was charged in his absence.
According to the charges laid out by prosecutors, the four "assigned themselves and other persons roles for the purpose of overthrowing the Federal Government of Nigeria by force of arms."
Okorie was to be the plot's financier, Adeka would co-ordinate planning, Kudambo was to recruit personnel while a fifth suspect, Lieutenant Tijani Abdallah, was assigned the task of collecting weapons, the court heard.
Mustapha used Okorie to pass money to Adballah "for the purpose of purchasing a Stinger surface-to-air missile to be used in shooting down the president's helicopter with the president on board", the charge sheet said.
Abdallah was said to have made several strips to the nearby west African countries of Togo and Ivory Coast and to have negotiated for the purchase of the missile, a sophisticated US-made shoulder-mounted weapon, it said.
"Between November 1, 2002 and March 2004 Commander Yakumbu Kudambo drafted the framework of a coup speech and the outlook of the intended government," the charge sheet, which was read before the court, said.
Judge Dan Abutu dismissed a defence request that the defendants be transferred to civilian custody and remanded them to remain in the charge of the Directorate of Military Intelligence's detention centre in Lagos.
The case was adjourned until October 28.