The US has carried out airstrikes against artillery used by Islamist militants in northern Iraq, the Pentagon says. It says it has begun strikes on artillery held by the Islamist rebels in the Kurdistan region.

Two F/A-18 aircraft dropped 500-pound laser-guided bombs on a mobile artillery piece near Irbil, the capital of the Kurdish region.

Rear Admiral John Kirby said in a statement that the Islamist militants had been using the artillery to shell Kurdish forces defending the city, where US personnel are located.

It follows approval by the US President Barack Obama for the airstikes against the Islamist figthers. He also confirmed US planes dropped aid to Iraqis trapped on a mountain.

The aircraft delivered food and water and safely left the drop zone, according to the US Defence Department.

President Obama said he had agreed to targeted strikes - if needed - to protect US citizens working in Irbil, and also to prevent a potential "genocide" of the Yazidi people.

But he stressed there was no intention of sending in any troops:

Meanwhile, after meeting in emergency session, the UN Security Council has strongly condemned attacks on Iraqi civilians by Islamic militants:

It comes as around 40,000 residents from the ancient Yazidi community were forced to leave the northern Iraqi town of Sinjar after Sunni fighters overwhelmed Kurdish forces.

Many of them are trapped on Mount Sinjar without food or water and are at risk of starvation as Islamist militants surround the base.

The President said the military would act to stop the advance on Irbil by The Islamic State - the group previously known as ISIS or ISIL. Irbil is the capital of the Kurdish region.

The US has a consulate in the city, where civilian and military staff work.

Humanitarian drops

C-130 and C-17 cargo aircraft participated in the aid drop on Mount Sinjar, and were escorted by F-18 fighters.

The planes dropped more than 20,000 litres of drinking water and 8,000 pre-packaged meals.

President Obama said the Iraqi government had asked the US for help, with as many as tens of thousands hiding on the mountain with "little but the clothes on their backs".

"Children are dying of thirst, meanwhile ISIL forces have called for the destruction of the entire Yazidi people, which would constitute genocide," the president said.

"These innocent families are faced with a horrible choice: Descend the mountain and be slaughtered, or stay and slowly die of thirst and hunger."

Airstrikes approved

Airstrikes had been approved to help Iraqi forces and stop a "massacre" of the Yazidis, said the President.

The Islamic State has issued the Yazidi people an ultimatum to convert to Islam, pay a religious fine, flee their homes or face death.

It sees the Yazidis, who are followers of a religion derived from Zoroastrianism, as "devil worshippers".

Attacks on minorities in Iraq could constitute a crime against humanity, said the UN Security Council at an emergency meeting on Thursday.

Hundreds of thousands of people, mostly Christians, are fleeing from the jihadists who have swept through more than a dozen towns in recent days.

Among them, the militants captured Iraq's biggest Christian town, Qaraqosh, prompting many residents to leave, fearing for their lives.

The group has declared a caliphate - an Islamic state - across much of Iraq and Syria and wants to bring in a strict version of Islamic law.

Originally published 07:12