Pope Leo on Sunday appealed for an immediate ceasefire and the opening of humanitarian corridors in Sudan, saying he was following with "great sorrow" reports of terrible brutality in the city of Al-Fashir in Darfur.

"Indiscriminate violence against women and children, attacks on defenceless civilians and serious obstacles to humanitarian action are causing unacceptable suffering," the pope said during his weekly Angelus address to crowds in St. Peter's Square.

He called on the international community to act "decisively and generously" to support relief efforts.

The U.N. human rights office said on Friday that hundreds of civilians and unarmed fighters may have been killed late last month when the paramilitary Rapid Support Forces captured Al-Fashir, the Sudanese army's last major holdout in Darfur.

The city fell a week ago after an 18-month siege, prompting tens of thousands to flee.

Pope Leo also addressed the situation in Tanzania on Sunday, saying there had been clashes with numerous casualties after recent national elections. He urged all sides to avoid violence and "walk the path of dialogue".