UNITED NATIONS, May 13 (Xinhua) -- The UN Security Council on Friday expressed alarm at the extremist group Boko Haram's linkages with the Islamic State, condemning all terrorist attacks by Boko Haram in the Lake Chad Basin region.

In a presidential statement adopted here, the 15-nation council also expressed its deep concern about the alarming scale of humanitarian crisis caused by Boko Haram in the region.

It noted that 2.2 million Nigerians are internally displaced and there are over 450,000 internally-displaced persons and refugees in neighboring Cameroon, Chad and Niger. And an estimated 4.2 million people in the Lake Chad Basin region face a food security crisis.

UN Under-Secretary-General for Humanitarian Affairs Stephen O' Brien will travel to Niger and Nigeria next week to take stock of the humanitarian crisis in the Lake Chad Basin, UN Spokesperson Stephane Dujarric told a daily briefing.

The presidential statement came one day before the Second Regional Security Summit on Saturday in Abuja, Nigeria to evaluate the regional response to the threat posed by Boko Haram with a view to adopting a comprehensive strategy to address the crisis.

The Security Council also urged member states participating in the joint force to counter Boko Haram to enhance regional military cooperation to deny safe haven to the group and allow humanitarian access.

Boko Haram's insurgency has killed tens of thousands of people and displaced millions. Nigeria is heading up a multinational joint task force along with Cameroon, Chad, Niger and Benin which was set up in March 2015.

Earlier this month, Nigerian troops have commenced large scale operations to flush out Boko Haram terrorists from their Sambisa forest hideout in restive Borno, north-eastern Nigeria.