BRUSSELS (AP) — The European Union’s top migration official expressed concern Friday about a spike in the number of shooting incidents on the Turkish side of the country’s land border with Greece near where EU border officers have been patrolling.

At least 3 incidents involving gunfire into the air by uniformed Turkish personnel have been reported recently. The EU’s border and coastguard agency chief Fabrice Leggeri has written to the European Commission to warn of the rising number of shootings in the Evros region.

“I am always concerned when there are shootings close to EU external borders,” EU Home Affairs Commissioner Ylva Johansson told reporters, “even if it seems that it has not been shooting at any persons.” No details about the incidents were provided.

Leggeri has ordered Frontex officers to wear bulletproof jackets when patrolling in the area.

Tensions along the borders between EU member country Greece and Turkey have long simmered. They spilled over into violence a year ago after Turkey, angered at a lack of EU support for its invasion into northern Syria, waved thousands of migrants through the borders.

EU leaders will discuss their tense relations with Turkey at a 2-day summit in Brussels starting March 25.