A niece and the doctor of Benin's President Thomas Boni Yayi are among three people charged in an alleged plot to poison him by switching his medication.

The state prosecutor says the niece, the doctor and former commerce minister Moudjaidou Soumanou have been arrested and charged with attempted murder and conspiracy for their roles in the alleged plot.

Prosecutors say the president's niece, Zouberath Kora, and his doctor, Ibrahim Mama Cisse, had been offered nearly $2 million for their roles in the scheme, which involved replacing the president's medication with a toxic substance while he was visiting Brussels this month.

Investigators say the scheme unraveled after the niece told a relative about the plot.

Prosecutors say the poisoning plot may have been launched by Patrice Talon, a local businessman who has recently been at odds with the president. Authorities have been seeking Talon, who is out of the country.

Mr. Yayi became Benin's president in 2006. The following year, he survived an attack in which gunmen ambushed his convoy.

He won re-election last year. The 60-year-old president currently serves as chairman of the African Union.