ISIL demanded officials and soldiers pledge allegiance to the caliphate they recently declared or face execution.

More than one million Iraqis have fled their homes over the month as ISIL terrorists seized Mosul, Tikrit and other cities in the north-west.

At least 2,461 people were killed in June, the UN and Iraqi officials say.

The refugees in the Kurdish-controlled town of Sinjar, near Tal Afar, told the BBC that towns and villages they had fled were now being systematically cleared by ISIL (the so-called Islamic State in Iraq and the Levant).

Many of the displaced are Shias, Christians and ethnic Kurds.

"For Shias, if they cannot be exchanged for prisoners, [the ISIL terrorists] would simply cut off their heads," said Hassan, a Kurd who had spent 16 days in captivity until his family paid $51,500 for his release.

Bashar al-Khiki, provincial leader who fled Mosul, said that the terrorists were "collecting information about people and compiling a database in order to identify those who work for the government or security forces".

"If they don't repent and pledge their allegiance to the caliphate, they will be killed. A lot of these people have disappeared in Mosul," he added.

Human rights groups have reported that ISIL militants have been going neighborhood to neighborhood in Mosul, deliberately targeting non-Sunnis and those opposed to them.

ISIL last week declared it was establishing a so-called caliphate on the territories under its control in Syria and Iraq.

BA/BA