'Brit' issues ISIS warning as US journalist's throat slit

Washington - The Islamic State (ISIS) has murdered a second American reporter, releasing another propaganda video on Tuesday showing a masked militant with a British accent cutting the throat of a US captive.

In the latest footage, 31-year-old reporter Steven Sotloff addresses the camera to say he is a victim of President Barack Obama's decision to press on with air strikes against the jihadists.

At the end of the five-minute recording, the IS militant presents another captive to the camera, identified in an on-screen caption as British, and implicitly threatens him with execution.

A US spokesperson said Washington was trying to authenticate the "sickening" footage, and British Prime Minister David Cameron said it depicted an "absolutely disgusting, despicable act".

The footage was almost identical to a video the Islamic State released last month in response to Obama's ordering US air strikes, and showing the murder of 40-year-old reporter James Foley.

US air strikes have continued since the first killing and on Tuesday appeared to bear fruit, as Iraqi forces made more progress in their fightback against the jihadists who have seized much of northern Iraq.

After breaking a months-long siege of the Shiite Turkmen town of Amerli, government troops also regained control of part of a key highway linking Baghdad to the north of the country.

Two towns north of Amerli had already been retaken on Monday as Iraqi forces - backed by US strikes - won their first major victories since the army's collapse across much of the north in June.

That collapse left about 1 700 soldiers who surrendered in jihadist hands, with many believed to have been executed.

In Baghdad, demanding to know the fate of their relatives in uniform, hundreds of angry family members stormed parliament, attacked MPs and began a sit-in in its main chamber, an official said.

 'Ethnic cleansing'

The jihadists have reportedly carried out widespread atrocities. On Tuesday, Amnesty International accused them of war crimes and ethnic cleansing.

The Sunni extremist group has declared an Islamic "caliphate" in regions under its control in Iraq and Syria.

In June, it swept through much of the Sunni Arab heartland north of Baghdad and then stormed minority Christian and Yazidi areas.

The extremist faction has carried out beheadings, crucifixions and public stonings, and Amnesty accused it of "war crimes, including mass summary killings and abductions" in areas it controls.

Assistance is now arriving in Amerli, brought in both by fighters and the United Nations, which said Tuesday it had "delivered 45 metric tons of life-saving supplies."

As an aid truck entered the town, one man who had fought to defend Amerli said it was the first time he had seen grapes in months.

The siege took a heavy toll on residents, including Umm Ahmed, who lost her husband and 10-year-old son to a mortar round, leaving her to raise their three daughters, the oldest of whom is eight.

There was "no food and no water to drink, and the children and the elderly were dying," she said.

A day after seizing Amerli, troops and Shi'ite militiamen on Monday retook Sulaiman Bek and Yankaja, two towns to its north that had been important militant strongholds.

Army Staff Lieutenant General Abdulamir al-Zaidi said government forces had regained control of a stretch of the main highway to northern Iraq that had been closed for almost three months.

"The way from Baghdad to Kirkuk has become secure," said the commander of the Shi'ite Badr militia, Transport Minister Hadi al-Ameri.

The United States carried out four air strikes in the Amerli area, effectively acting in support of operations involving militia forces that previously fought against US troops in Iraq.

The government's reliance on Shiite militiamen in this and other operations risks entrenching groups which themselves have a history of brutal sectarian killings.

Demands for UN hostages

But worries over the rise of IS seem to outweigh other concerns, with Western leaders warning the group poses a security risk far outside the areas under its control.

Fiji, meanwhile, revealed that al-Qaeda-linked rebels in Syria holding 45 of its United Nations peacekeepers hostage in the Golan Heights are demanding they be expunged from a UN terror blacklist.

The Fijians, part of the UN Disengagement Observer Force, were captured last Wednesday when Al-Nusra Front rebels stormed a Golan crossing into Israeli-occupied territory.