US Secretary of State John Kerry slammed the Islamic State group for "abhorrent" abuses on Tuesday after the jihadists boasted of selling captured women and girls as slaves.

Islamic State militants said abducted Yazidi women and children had been divided among its fighters according to sharia law.

Kerry described the act as despicable, and said the group "does not represent Islam."

"ISIL now proudly takes credit for the abduction, enslavement, rape, forced marriage and sale of several thousand... women and girls, some as young as 12 years old," Kerry said in a statement, referring to an alternative name for the jihadists.

"ISIL rationalizes its abhorrent treatment of these women and girls by claiming it is somehow sanctioned by religion. Wrong. Dead wrong."

Tens of thousands of Yazidis, a minority population mostly confined to northern Iraq, have been displaced by the four-month-old jihadist offensive in the region.

The United States has been leading an air campaign against the Islamic State group in Iraq since August 8.

Yazidi leaders and rights groups have said the community faces genocide, which was put forward by Washington as a reason for the military campaign.

Kerry called on the international community to condemn the "commodification of women and children as spoils of war, including through their subjection to horrific physical and sexual violence, intimidation, and deprivation of liberty."

He said the Islamic State group represented "the worst of humanity," contrasting its actions with those of recent Nobel Peace Prize winners Malala Yousafzai and Kailash Satyarthi.

Rights watchdog Amnesty International accused the Islamic State organization of widespread abuses, and said its members are committing war crimes.

Military commanders from the US-led coalition fighting the group -- which now includes around 60 countries -- met in Washington Tuesday to discuss the military campaign.

The White House said it was "succeeding" in its strategy to defeat the militants, who have taken over swaths of territory in Iraq and Syria.

Obama rallies coalition commanders against IS jihadists
Washington (AFP) Oct 15, 2014 - President Barack Obama attempted to rally allied commanders around his emerging strategy to defeat Islamic State jihadists on Tuesday, as the US-led air armada stepped up its raids in Syria.

Coalition jets carried out two dozen strikes to relieve pressure on Kobane, but Obama admitted to deep concern about the Syrian border town's fate and he warned of a long campaign ahead.

In Washington, the president and the US military's top officer General Martin Dempsey met senior commanders from more than 20 Western and Arab allies involved in the campaign.

"One of the things that has emerged from the discussions, both before I came and during my visit here, is that this is going to be a long-term campaign," Obama warned.

"There are not quick fixes involved. We're still at the early stages," he said, explaining that efforts were focused on breaking the siege of Kobane and on halting the IS advance in western Iraq.

"As with any military effort, there will be days of progress and there are going to be periods of setback, but our coalition is united behind this long-term effort," he added.

A US military official, summing up the situation, said: "the coalition has strategic momentum although ISIL has tactical momentum."

Islamic State, he added "is an adaptive enemy."

The coalition will also need to adapt "by leveraging all elements of power," he added, stressing that military action alone "will not be decisive."

- Obama worried about Kobane -

The military meeting, at an airbase outside Washington, came after allied warplanes carried out its latest raids: 21 strikes over two days around Kobane, a Kurdish town on Syria's border with Turkey.

The bombing was designed to halt an IS offensive which has seen jihadists push into the town, threatening a massacre under the noses of the Turkish troops and world media watching from the border.

A Syrian exile rights group reported that the latest strikes had at least saved Kobane from "falling entirely into the jihadists' hands," but Obama admitted he was still worried.

"At this point we're also focused on the fighting that is taking place in Iraq's Anbar province, and we're deeply concerned about the situation in and around the Syrian town of Kobane," Obama said.

IS fighters are now in almost complete control of Sunni-majority Anbar, Iraq's largest province, and are closing in on the western outskirts of Baghdad, headquarters of the Shiite-led government.

The talks marked the first time high-ranking officers from so many nations have come together since the US-led coalition was formed in September and which now, on paper, includes about 60 countries.

- Cautious ally -

Turkey, which has faced a three-decade Kurdish insurgency, has tightened security of its porous Syrian border after the fighting in Kobane sparked the exodus of 200,000 refugees.

But it remains a cautious ally. Turkey's troops have not intervened in Kobane despite being only a few hundred yards from the fighting, and it has yet to allow US jets to mount attacks from its territory.

Turkey further complicated issues Tuesday when officials in Ankara said that Turkish jets bombed Kurdish rebel targets in the southeast of the country in the first such strikes against the separatists since an increasingly fragile 2013 ceasefire.

Kurds say they do not want Turkish troops in Kobane but want Turkey to allow its territory to be used for passing weapons to Kurdish fighters defending the Syrian town, an idea Ankara has so far rejected.

One of the PKK chiefs said on Saturday that all fighters had been called back to Turkey and warned that the peace process was in danger of collapse.

France's President Francois Hollande urged the West's NATO ally to open the border to allow aid to reach Kurdish fighters mounting a desperate defense of the town, which "could fall at any moment."

And US Secretary of State John Kerry said that Ankara had at least allowed the US-led coalition use of "certain facilities" while agreeing to host and train Syrian fighters opposed to the Islamic State group.

Kurdish fighters were trying to push into the eastern sector of the town, under IS control, said the Syrian Observatory for Human Rights, a British-based rights group which has a wide network of sources inside Syria.

Meanwhile, Iraqi forces are reported to be under intensifying pressure in Anbar province, where the town of Heet fell to the IS advance on Monday, according to Iraqi military sources.

- Ammunition drop -

Pro-government forces in northern Iraq were under pressure near the strategic Baiji oil refinery, where US aircraft Sunday dropped supplies including food, water and ammunition to Iraqi troops for the first time.

In Baghdad, an Iraqi lawmaker and prominent Shiite militia leader, Ahmed al-Khafaji, was one of at least 21 people killed by a suicide car bomb in the Shiite neighborhood of Kadhimiyah.

The third bombing in Kadhimiyah in four days, Khafaji's killing was immediately claimed by the Islamic State group.