Germain Katanga, a Congolese national, sits in the courtroom of the ICC during the closing statements in the trial against Katanga and Ngudjolo Chui in The Hague May 15, 2012. REUTERS/Michael Kooren

KINSHASA (Reuters) - Democratic Republic of Congo said it would not free warlord Germain Katanga at the end of his International Criminal Court (ICC)-imposed jail term on Monday as it is investigating him for other offences including the killing of nine U.N. peacekeepers.

The decision to hold Katanga is the latest chapter in a conflict that flared up in northeastern Congo over a decade ago but has continued to scar the province of Ituri.

Katanga, former commander of a militia in Congo’s northeast, was convicted by The Hague-based tribunal in 2014 of murder, pillage and assaults on civilians during a 2003 raid on a village that killed some 200 people.

He was returned to the Congolese capital Kinshasa last month to serve the remaining weeks of his sentence. He had been scheduled to be the first ICC convict to be freed.

But Congo Justice Minister Alexis Thambwe said that Katanga would not be released on Monday as investigators were exploring other accusations against him.

“We want to interrogate him notably on the role he could have played in the assassination of nine blue helmets,” he said, referring to the U.N. peacekeeping mission in the country.

It was not clear when the justice department would make the decision on whether to prosecute Katanga further.

The ICC charges pertained exclusively to the 2003 attack on a village and did not cover the killing of the peacekeepers, who were killed in a separate attack in 2005.

Katanga’s Patriotic Resistance Force in Ituri (FRPI) is one of a constellation of rebel groups in the vast, chaotic central African country that have terrorized civilians and exploited its rich reserves of gold and other minerals.