LJUBLJANA (AFP) - Three ancient Mesopotamian sculptures, thought to have been excavated illegally in Syria or Iraq, have been found in a Slovenian refugee camp on the border with Croatia, police said on Wednesday.

The National Museum in Ljubljana confirmed the alabaster objects were authentic Mesopotamian temple figurines and probably dated back to third millennium BC.

"Since the objects have no registration or inventory signs, we believe they were excavated illegally," museum archeologist Peter Turk told state radio Slovenija.

"Their value on the black market might not be in the ten of thousands of euros but certainly several thousands of euros," he added.

Last September, Unesco warned that archaeological sites in Syria and Iraq were being looted "on an industrial scale" and the proceeds from the plunder were funding Islamic State in Iraq and Syria (ISIS) extremists.

The statuettes were most likely left behind by a migrant in early November when thousands of people arrived daily from Croatia, police spokesman Miran Sadl told AFP.

The extraordinary find only emerged now, after the National Museum had finished its evaluation.

Almost half a million migrants heading for northern Europe have crossed Slovenia since October 2015 following Hungary's decision to seal its borders for refugees.