Updated

JOHANNESBURG (AP) — Equatorial Guinea's government on Tuesday defended the execution of four alleged coup plotters just an hour after they were condemned in a case that Amnesty International called a "pretense of justice."

The main opposition coalition described the executions as "political assassinations."

The government of the oil-rich but impoverished Central African nation said in a statement that the former military and government officials were given a fair trial in open court. Two colonels defended them before a military tribunal, the government said on its website.

The four were convicted Saturday of terrorism, high treason, attempting to assassinate the head of state and to overthrow the government.

Others tried in the plot received jail sentences ranging from one to 20 years.

Amnesty International said the four men were abducted by Guinean security forces in January from neighboring Benin, where they had been living in exile for years, including during the Feb. 11, 2009 attack for which they were convicted.

It said the men were secretly detained at Black Beach, a prison notorious for torture, until they "confessed" to participating in the attack launched from the Indian Ocean on the seaside presidential palace.

Jose Abeso Nsue, Manuel Ndong Anseme, Alipio Ndong Asumu and Jacinto Micha Obiang were executed within an hour of the tribunal condemning them on Saturday, Amnesty International said.

Abeso Nsue had reportedly asked to see his family when the sentence was handed down, but when his wife and son arrived at the prison an hour later, he already had been executed, the organization said.

"Equatorial Guinea must put an end to the abductions, torture and executions it currently carries out under the pretense of justice," said Amnesty's Africa director, Erwin van der Borght.

The opposition Convergence for Social Democracy in Equatorial Guinea, CPDS by its Spanish acronym, called the executions "an atrocity." It said in a statement Tuesday that three of the accused had left military service some 20 years ago and should have been tried in an ordinary court along with the fourth man, who was a civilian.

The government of President Teodoro Obiang originally blamed Nigerian rebels for the attack and scores of Nigerians were rounded up, jailed and expelled from the country.

Obiang has survived numerous coup attempts since staging his own in 1979, in which his uncle — the then- president — was killed.

The most notorious was a botched 2008 attempt by British mercenary Simon Mann. Obiang pardoned Mann last year after he served 15 months of a 34-year sentence for scheming to overthrow the government.

Obiang is accused of running one of the most corrupt dictatorships in the world, making himself, his family and some cronies fabulously wealthy while the majority of the 600,000 people struggle in deep poverty. A quarter of the population lives in exile.