Militants from jihadist group the Islamic State of Iraq and the Levant (ISIL) have executed dozens of captured Iraqi security forces members, according to photos posted online.
The authenticity of the photos, which were shared on Twitter and elsewhere and said to have been taken in Salaheddin province, north of Baghdad, could not be independently confirmed.
The militants said in one photo caption that they executed hundreds of soldiers. The photos that were seen by AFP showed dozens of bodies.
A major offensive spearheaded by ISIL but also involving supporters of executed dictator Saddam Hussein has overrun all of one province and chunks of three others since it was launched on Monday.
In one photo, militants watch as men in civilian clothes, their backs bent, faces staring at the ground and feet bare, shuffle forward in a line.
The men are then loaded into trucks, including at least one captured security forces vehicle.
Another photo shows men being made to lie down in a shallow ditch, as militants including a man bearing the ISIL flag look on.
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A man in a yellow shirt seems to be pleading for his life. The assault rifle-armed militants are then shown apparently firing into the ditch.
Another picture shows a militant aiming his Kalashnikov assault rifle into a ditch holding a double line of men with their hands behind their backs, blood pooling in the sand.
A cloud of dust rises from the ditch, apparently from gunshots.
And photos also show a man wearing a red beret of the type issued to Iraqi soldiers holding his Kalashnikov in one hand as he fires into a line of men in what appears to be a third ditch.
The photos appear to show at least three separate places in which men were executed and possibly a fourth, though it is difficult to determine due to varying camera angles.
On Saturday, Iraqi security forces found the burned bodies of 12 policemen after retaking the town of Ishaqi north of Baghdad, pointing to another atrocity carried out by militants.
Security forces performed poorly when faced with the militant offensive, in some cases abandoning vehicles and positions and shedding uniforms to flee.
But they appear to be recovering from the initial shock of the onslaught, and have retaken some areas north of the capital.