Police in the West African state of Benin are hunting for the third alleged plotter suspected of mounting a failed coup to unseat the country's president.
Two men - one a cabinet member and one said to be linked to the ringleader of a previous plot - were arrested on Sunday, a BBC reporter in Benin said.
The third accomplice is thought to be in hiding in Equatorial Guinea.
A plot to poison President Thomas Boni Yayi was foiled in 2012, Benin officials say.
In a statement issued on Sunday, officials said the men were plotting to overthrow Mr Yayi and install a military government in Benin.
Mr Yayi has been out of the country, visiting Equatorial Guinea for an international summit in February.
The plan was to "to block the head of state from returning to Cotonou after his trip and to institute a military regime," state prosecutor Justin Gbenameto said.
Mr Gbenameto said Col Pamphile Zomahoun and accountant Johannes Dagnon were in custody and investigations were continuing, the AFP news agency reported.
The BBC's Vincent Nnanna, in Cotonou, says the accountant is the head of a major business and an associate of Patrice Talon, the man being held in connection with the 2012 poison plot.
The third suspect remains at large but Benin has an extradition treaty with Equatorial Guinea and authorities are hopeful of making an arrest, our reporter says.
There is an assumption that there is a link between the latest coup attempt and the 2012 plot, he adds.
Mr Yayi, 60, was first elected president in 2006 and re-elected in 2011. He recently completed a term as president of the African Union.
In 2007, he survived an ambush by gunmen who attacked his convoy during an election campaign tour.