Pope Francis has led a special prayer service in St. Peter's Basilica for peace in South Sudan and Congo.

Earlier this year he said he was studying the possibility of going to South Sudan, the African nation suffering from famine and civil war. But he told faithful Thursday evening that wasn't possible.

Francis said that, "with prayer we want to sow seeds of peace" in South Sudan and Congo. He called for courageous peace efforts through dialogue and negotiations.

Peace talks are aimed at finding a resolution to South Sudan's nearly four-year-old civil war.

In Congo, tensions over the continued tenure of President Joseph Kabila, whose official mandate ended in December 2016, have fueled deadly demonstrations. An election official recently said the presidential vote wouldn't be held until late 2018.