MARTHA'S VINEYARD, United States (AFP) - President Barack Obama said Thursday that US air strikes had broken the siege of an Iraqi mountain sheltering civilian refugees and that troops conducting reconnaissance there would be withdrawn.

But he added that US air strikes would continue against extremists from the so-called Islamic State or ISIL if they threaten US personnel and facilities in the region, including the Kurdish regional capital Arbil.

"The bottom line is - the situation on the mountain has greatly improved and Americans should be very proud of our efforts because the skill and professionalism of our military and the generosity of our people we broke the ISIL siege of Mount Sinjar," Mr Obama said in a statement to reporters during his vacation in Martha's Vineyard, Massachusetts.

"We helped save many innocent lives. Because of these efforts, we do not expect there to be an additional operation to evacuate people off the mountain and it's unlikely we're going to need to continue humanitarian air drops on the mountain," he said.

Mr Obama, a longtime sceptic of the use of US force in Iraq, last week authorised air strikes as he warned that thousands of members of the Yazidi community risked "genocide" as they fled to the mountain under pursuit from Islamic State extremists.

Mr Obama said that the United States would still carry out air strikes along with stepping up military assistance to Iraqi government and Kurdish forces battling the IS fighters.

"We will continue air strikes to protect our people and facilities in Iraq," said Mr Obama, who had cited the risk to the US consulate in Arbil as a reason for the military intervention.

Mr Obama, however, said that he still saw a threat to Iraqis, including Christians and Muslims, from ISIL which has vowed to kill anyone who does not share the militants' hardline Sunni Muslim beliefs.

"The situation remains dire for Iraqis subject to ISIL's terror throughout the country," Mr Obama said.

He also reiterated his call for an "inclusive" government, after throwing his support behind Haidar al-Abadi, who has been designated prime minister of Iraq and is seeking to form a government.

"We are urging Iraqis to come together to turn the tide against ISIL above all by seizing the enormous opportunity of forming a new inclusive government under the leadership of prime minister designate," Mr Obama said.

US officials have accused incumbent Iraqi premier Nouri al-Maliki of ruling too divisively on behalf of the country's Shi'ite majority.