MALABO, April 16 (Reuters) - Equatorial Guinea has arrested and tortured several opposition politicians, one of whom died in police custody, after the authorities said they discovered a weapons cache, Amnesty International said on Wednesday.
The London-based watchdog said it was concerned a deteriorating human rights situation in the tiny, oil-rich West African nation could overshadow parliamentary and municipal elections scheduled for May 4.
Amnesty said Saturnino Ncogo Mbomio, a member of the banned opposition Progress Party of Equatorial Guinea (PPGE), died in police custody the night of March 12 to 13.
Police said Mbomio suffered a fractured skull after falling from his bed in the notoriously rough Black Beach prison in the island capital of the former Spanish colony.
The authorities said Mbomio was arrested after the discovery of three guns and bullets in the boot of a car being exported from Spain. They said the cache was to be used in a coup planned by PPGE leader Severo Moto who lives in exile there.
A Spanish judge on Wednesday told Moto he must stay in jail pending trial on arms trafficking charges.
Amnesty said it had information Mbomio had been so severely tortured he could not stand during a search of his home, where police said they also discovered three assault rifles, a sniper rifle and a gun with a silencer buried under floorboards. Moto was arrested by Spanish authorities on Monday. He has also been linked to a failed 2004 coup by British mercenary Simon Mann, who is currently in Black Beach prison and expected to stand trial in May.
"We have had no complaint so far about the treatment of Simon Mann," said Amnesty researcher Narise Castro. "Conditions in Black Beach prison have improved enormously in recent months."
Seven other people believed to be past or present members of the PPGE have also been arrested. Four of them are still being held without charges and Amnesty said it had received information that at least one of them had been tortured.
The watchdog called on Equatorial Guinea to conduct an immediate investigation into Mbomio's death in compliance with international standards and release those held in custody unless they were charged with a crime.
Amnesty said it knew of at least three cases of torture that resulted in death last year, but that only one police official had been convicted, to six months in prison. It called on the government in Malabo to end torture.
Since toppling his uncle in a 1979 coup, President Teodoro Obiang Nguema has kept an iron grip on power.
The discovery of massive offshore oil reserves turned the sleepy backwater into sub-Saharan Africa's third-largest oil producer and prompted the failed 2004 coup.
Despite billions of dollars of oil revenues, Equatorial Guinea has struggled to improve dire health and education standards, and watchdogs such as Transparency International have denounced rampant corruption. (For full Reuters Africa coverage and to have your say on the top issues, visit: http://africa.reuters.com/ ) (Reporting by Daniel Flynn; Editing by Matthew Jones)
