Macedonia started building a fence on its border with Greece on Saturday to better control the influx of migrants passing through the Balkan country, an AFP photographer at the frontier said.
The extent of the barrier was not yet known, but the photographer said the army was using heavy machinery to build a 2.5-metre-high (8-foot) fence near the crossing point used by migrants at Gevgelija.
An army source also confirmed to AFP that they were building a fence without giving further details.
The source said the crossing from Greece to non-EU member Macedonia would remain open and that the fence was aimed at ensuring migrants did not try to slip across at other spots.
In a statement following the November 13 shooting and suicide attacks in Paris, Macedonian authorities said the army would examine the possibility of erecting a fence to limit the flow of migrants from Greece, but emphasised it did not plan to close the border.
Two of the suspected suicide bombers in the Paris attacks entered Europe through Greece on the same day in October, pretending to be refugees fleeing the war in Syria, according to French prosecutors.
Since then, countries along the migrant route through the Balkans have tightened restrictions on the wave of people crossing their borders by allowing entry only to those fleeing war-torn countries such as Syria, Afghanistan and Iraq.
The move has sparked protests from migrants that have been turned away.
About 200 migrants on Thursday tried to break through a barbed wire fence separating Greece from Macedonia.