Congolese President Joseph Kabila's suggestion that he might arrest war crimes suspect Bosco Ntaganda was a positive sign, but the arrest should be carried out immediately, Human Rights Watch said Friday.

The International Criminal Court (ICC) issued an arrest warrant in 2006 for Ntaganda, dubbed the "Terminator", on charges of war crimes for using child soldiers in his militia group.

While visiting the chronically violence-plagued province of Nord Kivu in the eastern Democratic Republic of Congo on Wednesday, Kabila indicated that Ntaganda, now a general in the Congolese army, could be arrested.

"President Kabila has put Ntaganda's arrest firmly on the agenda, which is a major step forward for justice in Congo," said Anneke Van Woudenberg, senior Africa researcher at HRW.

But Kabila should now "immediately order" Ntaganda's arrest "and promptly transfer him to The Hague," where the ICC is based, the rights group said in a statement.

Speaking publicly in the Nord Kivu capital Goma on Wednesday, Kabila said DR Congo had "more than a hundred reasons to arrest" Ntaganda, noted the arrest warrant against him, but said his government would not be forced to act "under pressure from the international community."

"Kabila's words should promptly result in a lawfully conducted arrest that will ensure Ntaganda goes straight to The Hague and civilians aren't harmed," Van Woudenberg said.

She decried that Ntaganda had been freely moving around the lakeside town of Goma, "flaunting his impunity like a medal of honour."

Ntaganda, a long-time rebel commander, was integrated into the army under a 2009 peace deal and Kinshasa has said his cooperation is crucial to stabilising the country's restive east.

The ICC arrest warrant cites crimes allegedly committed while he served as rebel leader in the northeastern Ituri province.