BELGRADE, Serbia (AP) — Serbia has asked for Russia's help in fighting a wildfire that has been raging for the past three days in a remote mountainous area on the border between Serbia and Bulgaria.

Hundreds of firefighters in both countries have been struggling to contain the blaze on the Stara Planina mountain. Officials say the effort has been hampered by strong winds and rugged terrain that is hard to reach.

Bulgaria's army on Tuesday dispatched helicopters and heavy machinery to fight the fire, which first erupted on the Bulgarian side of the mountain.

In Serbia, emergency official Predrag Maric says he expects an Ilyushin-76 plane to arrive from Russia in the coming days.

Russia and Serbia jointly run a disaster relief center in southern Serbia that has sparked Western concerns about Russian influence in the Balkans.