BOGOTA (Reuters) -The eldest son of Colombian President Gustavo Petro, Nicolas Petro, on Tuesday pled not guilty to charges of money laundering and illicit enrichment at a court in the capital.

Nicolas Petro was arrested on Saturday in the city of Barranquilla alongside his ex-wife, Daysuris del Carmen Vasquez, who was quoted in the press in March saying that two people accused of having ties to drug trafficking gave her former spouse cash to support the president's election campaign.

While Vasquez said the president was not aware of the dealings, the case represents a scandal that could hamper the Petro administration's pursuit of peace-and-surrender deals with armed groups and its ambitious reform agenda.

According to the charges, Nicolas Petro, a lawmaker in Atlantico province, received money from accused drug traffickers in exchange for including them in the president's peace plans.

"Your honor, I do not accept the charges," he told a judge during the hearing.

By denying the charges, Nicolas Petro lost the chance to secure a 50% reduction of any sentence if convicted.

Later in the hearing he pledged to collaborate with prosecutors.

"We have decided to begin a process of collaboration where I will relate new facts and situations that will help prosecutors," Nicolas Petro said.

The judge will make decision on Thursday as to whether or not the younger Petro will be held in jail as the process continues.

The president's son could receive a sentence of between 12 and 20 years if found guilty during a trial, according to lawyers. Vasquez also denied the charges of money laundering and violating data protection laws.

(Reporting by Luis Jaime Acosta; Writing by Oliver Griffin; Editing by Leslie Adler and Alistair Bell)