Nicolas Petro taken into custody on charges of money laundering and illicit enrichment.
The chief prosecutor’s office said in a statement that Nicolas Petro and his ex-wife Daysuris Vazquez were taken into custody on orders of a court in Bogota about 6am local time (11:00 GMT) on Saturday.
The office said that once brought before a judge, prosecutors would seek their provisional detention as it investigates the two over allegations of money laundering.
President Gustavo Petro said he would not interfere with the probe.
“As an individual and father, it pains me to see so much self-destruction and one of my sons going to jail,” Petro wrote on social media.
“As president of the republic, I’ve assured the chief prosecutor’s office that it will have all of the guarantees so it can proceed according to the law.”
He added that he wished his son “luck and strength.” “May these occurrences forge his character and may he reflect about his own errors,” the president said.
The arrest of Nicolas Petro is a major blow to the government, which has been buffeted by conservative attacks and struggled to maintain bipartisan support for Colombia in the United States, a key ally.
The president’s son had welcomed the investigation when it began in March and has previously called accusations that he took money from drug traffickers in exchange for including them in his father’s peace efforts unfounded.
Vazquez, earlier this year, told local media that two people accused of involvement with drug trafficking had given Nicolas money for his father’s campaign, among other alleged acts of corruption.
She alleged that the money was instead used it to live in luxury in the northern city of Barranquilla.
In an interview with the magazine Semana, Vazquez said that her former husband received the equivalent of $124,000 from a former drug trafficker named Samuel Santander Lopesierra, who served 18 years in prison in the US for drug trafficking.
Prosecutors confirmed the arrest of the younger Petro on charges of money laundering and illicit enrichment. Vasquez was also charged with the former offence.
President Petro has denied receiving money from the country’s powerful cocaine groups. He himself asked that his son be investigated.
His government has spearheaded a “Total Peace” proposal focused on persuading criminal groups to lay down their arms. Petro has pledged to make peace or surrender deals with rebels and crime gangs to end Colombia’s 60-year internal conflict, which has killed 450,000 people.
Efforts have met mixed success during his first year in office. Revived negotiations with the National Liberation Army (ELN) armed group have led to a ceasefire set to begin in August, while efforts to hold conversations with major crime gang the Clan del Golfo have faltered due to continued violence.