Benin said Sunday that authorities have thwarted an attempt to oust President Thomas Boni Yayi and install a military regime in the west African nation.
In a statement read to journalists, state prosecutor Justin Gbenameto said a colonel and businessman were arrested for plotting "to block the head of state from returning to Cotonou after his trip and to institute a military regime."
Yayi, who recently completed a one-year term as chairman of the African Union, had travelled to Equatorial Guinea last month for a summit with South American leaders.
Gbenameto said Colonel Pamphile Zomahoun and prominent accountant and businessman Johannes Dagnon were in custody and investigations were continuing.
Alleged plots against the government are not new for Benin.
Patrice Talon, a businessman linked to the cotton industry and former close associate of Yayi, was accused last year of masterminding a plot to replace the president's heart medication with poison.
Yayi's niece, his personal doctor and a former commerce minister have been charged as the key accomplices in the scheme, and the president's bodyguard was also detained for questioning.
Talon was arrested in Paris in December on an international warrant issued by Benin and was forced to surrender his passport before being released. A Paris appeals court is due to take up the case in this year.
Cotonou has also called for the arrest of a Talon associate, Olivier Bocco, who is believed to be outside Benin.
The motivation for the so-called poison plot has not yet been made clear, but the allegations have raised suspicions in Benin that they are intended to smear the president's enemies, and the opposition has criticised the case.
Speaking to journalists Sunday, state prosecutor Gbenameto said he was informed on February 22 by the security services about an attempted attack against the state.
An inquiry panel was then created "to shine light on the affair of the attempted coup d'etat," with investigations ultimately revealing that Zomahoun and Dagnon were involved in a plot to impose military rule, Gbenameto said.
He told AFP that "the ongoing investigation will determine the other accomplices, if there are any."
Yayi, 60, is an economist who first took office in 2006 and won re-election in 2011 with 53 percent of the vote.
The government's supporters argue that the president has made enemies while working to flush out corruption.
Nine people, including a cabinet minister, have been arrested in recent months over an alleged embezzlement scheme linked to abandoned plans to build a new parliament building.
But the government has been criticised for using the criminal justice system to silence opponents, including in the media and private sector.
Asked about the latest allegations, Yaya Pognon, secretary general of the main opposition party, Unity Makes the Nation, noted that "no objective proof has yet been put forward."
He said the public needed to learn more before forming a judgment about the charges.
Economic activity at Benin's main port and the cotton industry are the key sources of revenue in the nation of some nine million people.
While serving as AU chair, Yayi pushed strongly for a west African force to launch an offensive against Islamist rebels in Mali.