The U.N. Security Council is strongly condemning attacks by the Islamic extremist group Boko Haram and expressing alarm at its links to the Islamic State group ahead of a summit in Nigeria to evaluate efforts to combat the extremists.

A presidential statement approved Friday by all 15 council members demands that Boko Haram "immediately and unequivocally cease all violence and all abuses of human rights and violations of international humanitarian law." It also demands the immediate release of the thousands of people held captive by Boko Haram including 219 Nigerian schoolgirls abducted in April 2014.

The council welcomed Nigerian President Muhammadu Buhari's "crucial initiative" to convene Saturday's summit in the capital Abuja to evaluate the regional response to Boko Haram "with a view to adopting a comprehensive strategy to address the governance, security, development, socio-economic and humanitarian dimensions of the crisis."

Amnesty International called on leaders attending the summit to ensure that justice remains a priority and to increase efforts to protect civilians.

Some 20,000 people have died and 2.1 million become refugees in Boko Haram's nearly 7-year uprising to create an Islamic state but U.S.-backed African governments have made military advances against Islamic extremists.

Two bombings this week in the northeastern city of Maiduguri, the birthplace of Boko Haram and headquarters of the military's campaign against the jihadists, were the first attacks in two months. They indicated the success of heightened vigilance by soldiers and self-defence groups that have reported intercepting several suicide bombers recently.

The decrease in attacks, which were an almost daily occurrence earlier this year, also marks the success of the military campaign that officers say has Boko Haram hemmed into strongholds in the Sambisa Forest, a sprawling game reserve 45 minutes' drive southwest of Maiduguri.

Dozens of Boko Haram fighters are surrendering, reporting food and ammunition shortages, the military said this week.

News from © The Associated Press, 2016