Karim Wade is alleged to have acquired by corrupt means companies and real estate valued at $1.4bn, including land in Dakar, a fleet of luxury cars and a number of media and finance companies operating across Africa.
"Karim Wade will remain in prison and will go on trial in two months for illicit enrichment," the ministry of justice source told AFP.
The 45-year-old is also facing accusations relating to an unexplained sum of $205m which prosecutors say he deposited into several Monaco bank accounts.
An account in Singapore containing $95m was attributed to him this week.
Wade has been on remand in Dakar for a exactly year since his arrest and the city's anti-corruption court ordered that he remain in custody, the source said, adding that the exact sum for which he will be tried had not yet been determined.
Under Senegalese law, investigators would normally have had a maximum of six months to investigate Wade before sending him to trial or dismissing the case.
But the anti-corruption court extended the pre-trial detention period in October for another six months.
Wade refused last week to answer questions from investigating judges, stating that the "charges against me are political and fanciful", but he has consistently denied any wrongdoing and said his wealth was acquired legitimately.