The US President Barack Obama Thursday announced the authorisation of "targetted air strikes" in Iraq to stop the advance of Islamic State (IS) fighters, as well as humanitarian action to help Yazidi refugees trapped on a mountain.

"Today I authorised two operations in Iraq. Targetted air strikes to protect our American personnel and a humanitarian effort to help save thousands of Iraqi civilians who are trapped on a mountain without food or water and facing almost certain death," Obama said during a televised address on Thursday evening.

Explaining the reasons for the air strikes, he said:

"In recent days these terrorists have continued to move across Iraq and have neared the city of Erbil where American diplomats and civilians serve at our consulate and American military personnel advise Iraqi forces.

To stop the advance on Erbil, I have directed our military to take targetted strikes against ISIL terrorist convoys should they move towards the city. We intend to stay vigilant and take action if these terrorist forces threaten our forces or personnel any where in Iraq including our consulate in Erbil and our embassy in Baghdad.

We are providing urgent assistance to Iraqi government and Kurdish forces so they can more effectively wage the fight against ISIL."

Describing the plight of the Yazidi refugees, President Obama said America could not turn a blind eye to a "potential genocide".

“Thousands, perhaps tens of thousands [of Yazidis] are now hiding high up the mountain with little but the clothes on their backs, they are without food, they are without water. People are starving, children are dying of thirst. Meanwhile Isis forces below have called for the systematic destruction of the Yazidi people, which would constitute genocide," he said.

He went on to say:

"We have a mandate to help, in this case a request from the Iraqi government, and when we have the unique capabilities to help avert a massacre, I believe the USA cannot turn a blind eye. We can act carefully and responsibly to help prevent a potential act of genocide. That's what we are doing on that mountain."

"Therefore I authorised targetted air strikes, if necessary, to help forces in Iraq, as they fight to break the siege of Mount Sinjar as they fight to protect the civilians trapped there."

“Earlier this week, one Iraqi said no-one is coming to help. Well, today America is coming to help."

Acknowledging domestic concern and criticism of US action in Iraq after troops were only recently withdrawn, Obama stressed that there would not be any boots on the ground.

"I know that many of you are rightly concerned about any military action in Iraq, even limited strikes like these. I understand that. I ran for this office, in part to end our war in Iraq and welcome our troops home. That's what we have done," he said.

"As Commander in Chief, I will not allow the US to be dragged into fighting another war in Iraq, and so even as we support Iraqis as they take the fight to these terrorists, American combat troops will not be returning to fight in Iraq," he added.