The jihadist Islamic State of Iraq and the Levant posted pictures online of militants bulldozing a berm dividing Iraq and Syria, symbolising its goal of uniting its forces in the two countries.
The jihadists could be seen clearing a road through the berm, before trucks drove through as a militant stood nearby holding the group's black flag, in photos shared on websites and Twitter.
Creating a cross-border Islamic state is one of the group's main aims.
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The first shot was dated June 10 and carried the title of the photo series, "Smashing the Sykes-Picot border" -- a reference to the agreement between Britain and France that carved up the Middle East after World War I, with the former taking Iraq and the latter Syria.
Another photo showed a militant standing in front of Iraqi army Humvees and trucks, suggesting the shots were taken after the launch of a jihadist offensive this week in which large numbers of military vehicles were captured.
But the authenticity of the photos could not be independently verified.
ISIL has overrun all of Nineveh province, and parts of Kirkuk province to its southeast and Salaheddin to its south.
The offensive reached as far as the outskirts of Samarra, just 110 kilometres (70 miles) north of Baghdad, before clashes between security forces and militants ended without them entering the city.