The son of the Colombian president has been arrested as part of a high-profile money-laundering investigation into funds he allegedly collected from convicted drug traffickers during last year’s presidential campaign. The president, Gustavo Petro, a former rebel who rose through Colombia’s political ranks as an anti-corruption crusader, said he would not interfere with the investigation. Petro said in an early morning message on X, the social media platform formerly known as Twitter: “As an individual and father, it pains me to see so much self destruction and one of my sons going to jail. “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.” The arrest of Nicolás Petro is a large blow to the government, which has been buffeted by conservative attacks at the same time as it has struggled to maintain bipartisan support for Colombia in the US, a longtime ally in the “war on drugs” and the fight against illegal armed groups. The investigation stems from declarations made by Nicolás Petro’s ex-wife, Daysuris del Carmen Vásquez, to the local media outlet Semana this year. In the interview, Vásquez said she was present at meetings when her husband arranged a donation of more than 600m pesos (about £120,000) from a politician once convicted in Washington of drug trafficking and who was seeking the Petro campaign’s support to resume his political career. She said President Petro was unaware of his son’s dealings and that the money he collected in his campaign’s name was kept in a safe at the couple’s home in the coastal city of Barranquilla. Nicolás Petro has denied his ex-wife’s claims and said they were unfounded. The chief prosecutor’s office said in a statement that Nicolás Petro and his ex-wife were taken into custody on orders of a court in Bogotá at about 6am local time on Saturday. It said that prosecutors would seek their provisional detention once they were brought before a judge while it investigated the two for money laundering.