(In July 29 story, adds dropped paragraphs on detention of Nicolas Petro's ex-wife)

BOGOTA (Reuters) -Nicolas Petro, son of Colombian President Gustavo Petro, has been arrested as part of an investigation into money laundering and illicit enrichment, the attorney general's office said early on Saturday.

The younger Petro, a politician in Atlantico province, 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 to end civil strife unfounded and harmful.

Also arrested on money laundering and personal data violation accusations was Nicolas' ex-wife Daysuris del Carmen Vasquez, who earlier this year told local media two people accused of involvement with drug trafficking had given Nicolas money for his father's campaign.

The president's son was taken on a plane to the attorney general's office headquarters in capital Bogota from the city of Barranquilla, according to sources from the police and the prosecutor's office.

Colombian media showed videos of both being escorted to a government plane by security agents in armored vehicles and motorcycles.

Petro said on X, the platform previously known as Twitter, that it was painful for one of his children to be jailed, but that the attorney general's office had all guarantees to proceed according to the law.

"To my son I wish luck and strength. May these occurrences forge his character and may he reflect about his own errors," the president said. "As I affirmed to the attorney general I will not intervene nor pressure his decisions, may the law freely guide the process."

Colombia's procurator said in a separate statement it will intervene in the upcoming hearings of Petro's son and his ex-wife to ensure the legal system is respected, as well as the fundamental rights and guarantees of all parties.

The president 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 been met with mixed success during his first year in office. Revived negotiations with the National Liberation Army (ELN) guerrilla 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.

A proposed law to regulate crime group surrenders, giving participants lower sentences in exchange for information and restorative work, has drawn harsh critique including from the attorney general.

The attorney general's office will request to a judge that the younger Petro and Vasquez be held on the charges, it said.

"Charges will be formulated for the aforementioned crimes and liberty restriction measures will be requested," the attorney general's office said in a statement.

(Reporting by Julia Symmes Cobb and Luis Jaime Acosta; editing by Diane Craft and Alistair Bell)