Ukraine denies targeting Bulgaria as drone explodes near pipeline, Kyiv promises inquiry

Ukraine denied on Saturday targeting Bulgaria after a drone exploded close to the strategic Trans-Balkan gas pipeline linking Turkey to Ukraine near the Romanian border.

Bulgaria's defence ministry said the drone was of a type "widely used by the Ukrainian military", and the foreign minister summoned the Ukrainian ambassador for a meeting on Monday in response, her office said.

Kyiv said it was "in close contact with the Bulgarian side to clarify the circumstances" of the incident, the latest case of a drone straying into NATO airspace as Ukraine fights off Russia's invasion.

"We can say with certainty that the Ukrainian Armed Forces did not intentionally direct any assets toward Bulgaria," Ukraine's foreign ministry spokesman Georgiy Tykhyi said, blaming Russia's invasion for the incident.

While the explosion caused no casualties, Bulgarian Prime Minister Rumen Radev said the amount of explosives it was carrying was "significant".

"The drone exploded in the immediate vicinity of the Kardam border-crossing with Romania," near the Black Sea in the country's northeast, "1,000 metres from the Trans-Balkan gas pipeline's compressor station," he said in a video released by the government.

The drone eventually crashed into a sunflower field, Radev said.

Romania border police recorded the sound of the drone, then a Bulgarian border police patrol spotted "a loud explosion accompanied by black smoke", Radev added, speaking after an extraordinary meeting of his cabinet's security council.

"One thing is certain: the drone was carrying a significant amount of explosives, given that it could be heard from a distance and produced such black smoke," he said.

The drone had not been detected by either of the two neighbouring countries, he said, adding: "As you know, identifying and neutralising these drones poses a major challenge."