Obama says US will not relent in fight against Islamic State

President Barack Obama has said the United States and its allies would not relent in its fight to combat Islamic State sand would hunt down their leaders and cut off the group's financing.

"Destroying (Islamic State) is not only a realistic goal, were going to get it done," he told a news conference on Sunday after the Asean Summit and East Asia Summit meetings in Kuala Lumpur, Malaysia.

“We will destroy them. We will take back land they are currently in, take out their financing, hunt down leadership, dismantle their networks, supply lines and we will destroy them.”

Mr Obama said it "would be helpful" if Russia directed its focus on tackling Islamic State and he hoped Moscow would agree to a leadership transition in Syria that meant its president stepping down.

Russian president Vladimir Putin said on Saturday he wanted global cooperation to combat terrorism after Islamist militants killed 19 people, including six Russians, in an attack on a luxury hotel in Mali.

United Nations secretary general Ban Ki-moon said on Sunday he has urged Russia and the United States to cooperate on rooting out terrorism.

“All these terrorists and ideology extremists should be defeated in the name of humanity,” he said in Kuala Lumpur.

“In that regard, we need to unite. We need to show global solidarity to address the common enemy of ISIL, Daesh, some other extremists and terrorist groups,” he said, referring to Islamic State.