LYON, France (Reuters) - French prosecutors have charged two French men over a suspected plot to assassinate an opposition politician from Congo Republic living in the Paris region, an official from the prosecutor’s office said on Friday.

The two men were charged in the city of Lyon on Wednesday with association with criminals and possession of explosives, the official said without naming the target or giving details of the plot.

A third man suspected of involvement in the case was arrested as a witness but has not been charged, the official added.

A Congolese government spokesman could not be immediately reached for comment.

Human rights groups often criticize Congolese authorities for heavy-handed tactics toward opposition leaders and demonstrators.

Several prominent opponents of President Denis Sassou Nguesso have been jailed in recent years. Ex-army chief and presidential candidate Jean-Marie Michel Mokoko was sentenced in May to 20 years in prison for violating state security and illegally possessing weapons.