LAGOS, Nigeria (AP) – The Nigerian government for the first time Thursday publicly disclosed a foiled coup plot, charging four military officers and a civilian with conspiring to topple the government by shooting down a helicopter carrying President Olusegun Obasanjo.

Maj. Hamza al-Mustapha, former chief of personal security to late military dictator Gen. Sani Abacha, and four others, were each charged with two counts of treason in a federal high court in Lagos. If convicted, they could face the death penalty.

Abacha was the last in a line of military dictators that have repeatedly seized power in Nigeria, which has known only 15 years of democracy since independence from Britain in 1960. Years of corrupt and dictatorial rule has left Nigeria destitute, despite the fact it is Africa’s most populous country with 126 million people and the continent’s largest oil producer.

According to court documents, the officers engaged in a conspiracy “for the purpose of overthrowing the federal government of Nigeria by force of arms” and had sought to buy a “Stinger surface-to-air missile to be used in shooting down the president’s helicopter with the president on board.”

The documents did not say when the attack was to take place, but the three of the five charged Thursday were among dozens of military officers arrested and interrogated by Nigeria’s security agencies in April over what the government described at the time as “a security breach.”

Al-Mustapha, who has been in detention since 1999 over a series of assassinations of political opponents during Abacha’s years in power, was questioned in April by military intelligence officials in connection with the security breach.

Al-Mustapha, Lt. Col. Mohammed ibn Umar Adeka and civilian Onwuchekwa Okorie pleaded not guilty Thursday.

Two other suspects – navy Cmdr. Yakubu Kudambo, who escaped following his April arrest, and Lt. Tijani Abdallah – remain at large and were charged in absentia.

Judge Dan Abutu set the next hearing date for Oct. 28 and ordered the accused to remain in military custody.

AP-ES-10-21-04 1728EDT