US defence chief Ash Carter has said that the Pentagon was deploying a specialised operations force which would "over time" conduct unilateral operations in Iraq and Syria as part of US military campaign against the Islamic State (Isis).

"These special operators will over time be able to conduct raids, free hostages, gather intelligence, and capture IS leaders," Xinhua quoted Carter as saying in Washington on Tuesday.

He added that the creation of the specialised operations force was a result of "full coordination" with the Iraqi government.

"The raids in Iraq will be done at the invitation of the Iraqi government and focused on defending its borders and building the Iraqi Security Forces' own capability," Carter said.

Carter added that the force would also be in a position to conduct unilateral operations in Syria.

"That creates a virtuous cycle of better intelligence, which generates more targets, more raids, and more momentum," he said.

Carter also said that Turkey and other countries should do more in the fight against the Islamic State (IS), including the tightening of the border, Xinhua reported.

"France has been galvanised by the attacks on its capital and the French have intensified their role," said Carter in Washington at a congressional hearing.

"But we all must do more. Turkey must do more to control its often porous border," said Carter, noting that Saudi Arabia and the Gulf states' participation in campaign against the IS had been distracted by the conflict in Yemen.

"The more contributions we receive from other nations, the greater combat power we can achieve using our own forces," Carter added.

Carter's remarks came just hours after US President Barack Obama said at a press conference at the Paris Climate Summit that he had "repeated conversations" with Turkish President Recep Tayyip Erdogan about the need to close the border between Turkey and Syria.