BOGOTA (Reuters) - Colombia’s constitutional court said on Wednesday it cannot rule on whether potential changes to legislation that implements a peace deal with Marxist rebels are constitutional until after they are approved by congress.

People participate in a protest against Colombia's President Ivan Duque's call for changes to the Special Jurisdiction for Peace (JEP) law, in Bogota, Colombia March 18, 2019. The writing on the poster reads "Let's defend peace." REUTERS/Carlos Julio Martinez

President Ivan Duque, who says the 2016 accord is too easy on former members of the Revolutionary Armed Forces of Colombia (FARC), has asked legislators to review six parts of the law that regulates a special tribunal tasked with trying war crimes.

The Special Jurisdiction for Peace (JEP) court is meant to investigate, hear prosecutions and sentence those judged responsible for massacres, sexual violence and other crimes during the FARC’s five-decade war with the government.

“At this time the process has not been finished in congress - which is the body tasked with deliberating the objections,” court magistrate Gloria Stella Ortiz told journalists.

Duque, who was elected on a promise to modify the peace deal, says the law should better clarify extradition rules and that the FARC must repay its victims with assets.

He also wants to toughen sentencing and objected to the suspension of investigations by ordinary authorities into cases submitted to the JEP.

Duque also asked congress to exclude sexual crimes from the tribunal’s remit.

All laws associated with the accord were approved by the previous congress, whose term ended last year, and most points received the blessing of the court in previous rulings.

Duque will need a two-thirds majority to modify the laws, which are now part of the country’s constitution.

His coalition has a slender majority in the Senate and less than half of the seats in the lower house, making substantive changes to the laws unlikely.