Pope Francis denounced the surge in fighting in eastern Ukraine, saying it was a "scandal" that Christians were fighting among themselves.

During his weekly general audience Wednesday, Francis called for greater international efforts to bring Russian-backed separatists and Ukrainian troops back to negotiations.

See also: Grim scenes as civilians flee eastern Ukraine

The U.N. says indiscriminate shelling and an escalation in the fighting have killed at least 224 civilians in the past three weeks, raising the overall death toll to 5,358 people since April.

Two bodies in a residential area in Mariupol, Ukraine, after shelling earlier on January 24, 2015. Image: Sergey Vaganov/Associated Press

Francis said: "I think about you, Ukrainian brothers and sisters, and I think that this is a war among Christians! You have the same baptism, and you're fighting among Christians. Think about this, this scandal."

In urging prayers for peace, he said prayer was a "protest before God in times of war."