A special adviser to Equatorial Guinea's president has accused Spain of involvement in an alleged plot to overthrow the government.
Equatorial Guinea's President Obiang Nguema came to power in 1979 in a coup
The adviser, Miguel Mifuno, claimed Spain sent a warship with 500 marines to help a coup attempt in the former colony three months ago.
The trial of 17 alleged mercenaries is expected to begin in Equatorial Guinea within several weeks.
A spokeswoman for the Spanish government has denied the allegations.
"Our intelligence sources say that the warship was going to arrive on the same date that the coup attempt was going to take play - 8 March," Mr Mifuno told British newspaper The Guardian.
"It was already in our territorial waters with 500 soldiers aboard. Meanwhile there was a team of foreign mercenaries already in Equatorial Guinea who knew where we lived. They had plans to kill 50 people and to arrest others," he said.
Mr Mifuno also accused the Spanish government of funding opposition groups in exile.
The head of Equatorial Guinea's self-proclaimed government in exile, Severo Moto, who lives in Spain, has insisted he knew nothing about any alleged coup plot.
A further 70 alleged mercenaries are held in Zimbabwe on suspicion of being involved in the March coup plot.
The Zimbabwean authorities have begun legal moves to have them extradited to Equatorial Guinea.
One of the alleged mercenaries in Equatorial Guinea, a German national, died of cerebral malaria whilst in detention.