Listyo’s statement came on Monday after he met with Coordinating Political, Legal and Security Affairs Minister Mahfud MD and Indonesian Military (TNI) chief Adm. Yudo Margono.

With preparations for the 2024 legislative elections now in full swing, several major parties have reiterated their stiff opposition to the petition under review at the Constitutional Court, which calls for the restoration of closed-list elections just in time for next year’s race.

Listyo said if the police found any indication of a crime in relation to the leak, a formal investigation would be launched.

“We will take action according to [Mahfud’s instructions] to carry out a probe,” the police chief said, as quoted by Kompas.id.

Mahfud said Constitutional Court rulings were confidential until they were officially handed down. He claimed leaking such information was wrong and called on the police to investigate the incident.

"If [the court's decision] was leaked, that would be wrong. Those who did wrong are the ones who leaked [the information] from the inside," Mahfud said.

Read also: Court ruling ‘leak’ revives opposition to closed-list election

Mahfud called on the Constitutional Court to launch an internal investigation to identify who was responsible for the leak.

He added that according to the court’s clerks, the information was simply an analysis of the justices' stance from an outsider's point of view. The justices had yet to reach a verdict, they claimed, and were awaiting another hearing on Wednesday.

Denny Indrayana, the opposition figure and former deputy law and human rights minister who released the information, has said he obtained it from an unnamed yet reliable source.

Denny, who served as a minister under president Susilo Bambang Yudhoyono, said on Sunday that the Constitutional Court would rule in favor of the plaintiff, the ruling Indonesian Democratic Party of Struggle (PDI-P), meaning the 2024 legislative elections would be held under a closed-list system, in a six-to-three decision by the court.

Read also: Closed-list system may give PDI-P edge over rivals

The PDI-P filed a petition in November demanding the reinstatement of the closed-list electoral system. In such a system, voters select not a particular candidate but a party as a whole, which then chooses its own representatives in the House of Representatives according to the proportion of the vote it won.

The court has so far held 16 hearings on the petition

The proposed return to the closed-list system has faced massive pushback from politicians across the spectrum, who prefer the current system of direct legislative elections and who defend it as progressive and characteristic of Indonesian democracy.

Political experts say a return to closed-list elections would benefit parties with a loyal voter bases such as the PDI-P, while putting others that rely on the popularity of individual candidates at a disadvantage.