MANILA — President Benigno S. Aquino III announced Sunday that the Philippine government had reached a deal with a major rebel group that officials hope will reduce the persistent violence in the southern part of the country.

“This framework agreement paves the way for a final, enduring peace in Mindanao,” Mr. Aquino said.

The deal with the rebel group, the Moro Islamic Liberation Front, which has fought a war of independence for more than three decades, is the first step in what is expected to be a long, complex process of working through disputes that have lasted for centuries between the Christian-dominated national government and the predominantly Muslim residents of the southern island of Mindanao.

If the agreement succeeds in significantly reducing violence in Mindanao, it will be a historic achievement and a major political victory for Mr. Aquino, who has been heavily criticized in recent weeks for some of his legislative proposals.

Every Philippine president since the 1970s has tried to address the violence in Mindanao, which has claimed an estimated 120,000 lives and displaced more than two million people.