ADDIS ABABA, Ethiopia (AP) — The leaders of the United Nations and the African Union urged stronger international cooperation at the opening Sunday of the African Union summit in the Ethiopian capital, Addis Ababa.

"I strongly believe Africa is one of the greatest forces for good in our world," said U.N. Secretary-General Antonio Guterres. He said he wants to mobilize greater support for U.N. peacekeeping forces in Africa, including those battling extremist violence in Somalia, Nigeria and in West Africa.

African Union Commission chairman Moussa Faki Mahamat warned against the "rise of national egoism," which some took as a veiled reference to U.S. President Donald Trump. He urged South Sudan's warring factions to reach a peace agreement or risk African Union sanctions. Mahamat also urged Congo to hold elections later this year, according to schedule.

The summit is expected to issue a response to Trump's recent comment in which he likened African countries to a filthy toilet.

Among the leaders gathered for the annual summit of the African Union's 55 countries are the new leaders of Zimbabwe, Liberia and Angola.

Palestinian leader Mamhoud Abbas is attending the summit and asking African leaders not to open diplomatic representations in Jerusalem.