VATICAN CITY, Holy See - Pope Francis on Sunday urged leaders of the Democratic Republic of Congo to act quickly to resolve its political crisis and curb violence, condemning in particular the use of child soldiers.

Violence has flared across the country in recent months, including deadly confrontations in the Kasai regions, as President Joseph Kabila has indicated no plans to step down even though his term ended in December.

On Friday, a video emerged appearing to show DR Congo soldiers killing unarmed civilians in Kasai-Oriental, while on Saturday officials said militiamen from the country's Nande ethnic group had killed 25 civilians in the country's violence-torn east, most hacked to death with machetes.

"We continue to hear news sadly of violent and brutal clashes in the Kasai-Central region of the Democratic Republic of Congo," Francis said during his Angelus address in Saint Peter's Square.

"I strongly feel the pain of the victims, especially the many children ripped from their families and from schools to be used as soldiers," he said.

He made "an urgent appeal" to "national authorities and the international community, so that they take appropriate and prompt decisions" to end the violence.

Hundreds have died in central Congo in recent months and tens of thousands have been forced to flee as battles rage between security forces and militias.

Kabila, in power since 2001, was to step down on December 20 at the end of his second and final term, but refused to do so.

A deal brokered by the country's influential Roman Catholic bishops allows him to stay in office until late 2017 in tandem with a transitional body and a new premier.

But efforts to avoid all-out conflict in the country of 71 million people appear to have broken down, negotiations between the government and opposition parties having stalled.

Francis, 80, also urged prayers for victims of war and violence in other parts of Africa and across the world.

He denounced in particular the "cruel terrorist acts" in Pakistan, where at least 88 people were killed on Thursday when an attacker blew himself up inside a crowded Sufi shrine, for which the Islamic State group claimed responsibility.

The attack came after a series of bloody assaults, including a Taliban suicide bomb in the eastern city of Lahore which killed 13 people and wounded dozens. — Agence France-Presse