Around 130 US military advisors have arrived in Kurdish regional capital Arbil and "a group of them should be going to Mount Sinjar to study the situation there," Halgord Hekmat told AFP, without specifying whether they had yet done so.

US President Barack Obama has pledged to help save the tens of thousands of members of minority groups, mainly Yazidis, stranded on Mount Sinjar, threatened by militants from the Islamic State (IS) jihadist group and a worsening humanitarian situation.

"There are a range of options. I don't want to get ahead of decisions that haven't been made yet. We're going to rely on what the teams report back in terms of their assessment," Deputy National Security Advisor Ben Rhodes said Wednesday.

"But you look at corridors, you look at airlifts.... That's exactly what our team is doing on the ground now in Iraq," he explained, without specifying exactly where and when.

On Tuesday, Defence Secretary Chuck Hagel announced the deployment of 130 additional military advisors to Arbil, capital of the autonomous Kurdish region in northern Iraq, to give a "more in-depth assessment" of how to help the trapped Iraqis.

Rhodes added Obama was going to make a decision "in a matter of days."