Pakistan, Aug. 9 -- A drone entered Bulgaria and exploded near a major gas pipeline linking Turkey and Ukraine, prompting increased security measures. No casualties were reported after the incident near Bulgaria's border with Romania.

Bulgarian Prime Minister Rumen Radev said the drone exploded near the Kardam border crossing in northeastern Bulgaria. The blast occurred about 1,000 meters from a compressor station on the Trans-Balkan gas pipeline.

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Radev said authorities had not determined the drone's origin or type. He added that the drone later crashed in a nearby sunflower field after carrying what appeared to be significant explosives.

Romanian border police rep...