The Constitutional Court said Thursday that the establishment of a powerful anti-corruption investigation agency is constitutional, clearing the way for the new body's full operation.

The court said the Corruption Investigation Office for High-ranking Officials (CIO) essentially belongs to the executive branch and thus a law governing its status does not violate the principle of separation of powers stipulated in the Constitution.

It noted that running the agency independently from the executive branch does not mean it contradicts the principle, considering the importance of maintaining political neutrality and working as checks and balances against the prosecution.

The ruling was made in response to two complaints filed in February and May by lawmakers from the major opposition United Frontier Party (now the People Power Party) and others, who claimed that the agency violates the constitutional value of separation of powers.

The court also dismissed most of the other claims raised by the lawmakers, including the agency's alleged infringement of the prosecution's investigative authority.

It said prosecutors as defined under the Constitution are not limited to those in the prosecution service, citing those working in the military tribunal or special counsels.

But the judges were divided on the article of the law that allows the CIO to supersede other investigative agencies and to have the power to require them to transfer a case involving high-ranking officials.

The agency, designed to uproot corruption among high-ranking officials, officially began operation last Thursday. Kim Jin-wook, a 54-year-old former judge, took office as its inaugural director general and will lead a team of 25 prosecutors and 40 investigators, among others.

The agency is authorized to investigate corruption cases involving former and current public officials, including the president, and their families. It also has the power to indict when it comes to crimes involving the chief justice, prosecutor general, judges, prosecutors, high-ranking police and military officials.

Following the court's ruling, Kim said he and the rest of the CIO were ready to move forward.

He also addressed concerns that prosecutors with particular political biases, one way or the other, could be assigned to work at his new agency.

"If members of the panel recommended by both the ruling and opposition parties state their cases and make their voices heard, then I don't think (political bias) will be an issue," Kim said. "As I insisted at my inauguration, the CIO will adhere to political neutrality and independence and will investigate corruption by high-ranking officials fairly and squarely."

Kim also said the CIO won't have quite the rigid, top-down structure of the prosecution service.

"I'd like to create a horizontal organizational culture with open lines of communication," Kim said. "I want to build a creative organization, a place where people want to work."

As his No. 2 man, Kim nominated a judge-turned-attorney, Yeo Woon-kook. The 53-year-old Yeo served as a judge for nearly two decades, starting in the mid-1990s, and joined a local law firm in 2016.

Yeo is the vice chairman of the Korean Bar Association. Earlier this week, the organization recommended Yeo as a replacement for the outgoing Supreme Court justice Park Sang-ok.

Kim said Yeo, as an expert in criminal law, should complement him well at the CIO. (Yonhap)