Ukraine has denied targeting Bulgaria after a drone exploded close to the strategic Trans-Balkan gas pipeline, which links Türkiye to Ukraine, near the Romanian border.The drone entered Bulgarian airspace from Romania's airspace at 8:10am on Saturday, local time, Bulgarian Prime Minister Rumen Radev said in a social media video, and exploded 1 kilometre from the pipeline's compressor station near the north-eastern border village of Kardam.The sound of the drone was recorded by border police in Romania, then "a loud explosion accompanied by black smoke" was spotted by a Bulgarian border police patrol, Mr 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.While Mr Radev did not specify where the drone came from, Bulgaria's Defence Ministry later said the drone was most likely a Maya decoy drone according to initial analysis. This type of drone, it said, is widely used by the Ukrainian armed forces.It added: "Currently, nothing suggests that this was a deliberate incident."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.The drone eventually crashed into a sunflower field, Mr Radev said. It caused no casualties or infrastructure damage.He noted that the drone had not been detected by either of the two neighbouring countries, promising the security of strategic sites in the country and surveillance along the Bulgaria-Romania border would be increased."As you know, identifying and neutralising these drones poses a major challenge."Drone incursions that Western governments have linked to the Russia-Ukraine war have increased in frequency and raised anxiety that members of the NATO alliance need to bolster their defences against security threats.Bulgaria and Romania front onto the Black Sea, which is an arena of drone combat by both Ukraine and Russia.Turkish Foreign Minister Hakan Fidan said on Saturday that Ankara had conveyed to Russia and Ukraine they should declare a moratorium on their attacks in the Black Sea.Speaking to the state-run Anadolu news agency, Mr Fidan said Türkiye had conveyed its concerns about attacks on vessels in the Black Sea to both countries and was implementing certain security measures of its own, but did not elaborate further.Hakan Fidan says Ankara has conveyed to Russia and Ukraine they should declare a moratorium on their attacks in Black Sea. (Reuters: Alaa Al Sukhni)Russian strikes kill fourPresident Volodymyr Zelenskyy warned on Saturday, during a visit to Belgrade, that Ukraine was facing a winter with basically no working thermal power plants as overnight Russian strikes left four dead, including a child, in the Kyiv region."Russian missiles are aimed precisely at making the lives of Ukrainians unbearable," Mr Zelenskyy told reporters during his first official visit to Belgrade, highlighting that the attacks often target Ukraine's energy infrastructure.Ukraine was left with "virtually no intact thermal power plants" as it braced for the upcoming heating season, Mr Zelenskyy said. Those plants are important complements to the nuclear energy that also feeds its grid.The visit came after Russia launched another overnight barrage of missiles and drones, hitting mainly the capital and its surrounds.Ukrainian President Volodymyr Zelenskiy attends a press conference with Serbian President Aleksandar Vucic (not pictured) during his visit to Belgrade, Serbia, August 8, 2026. (Reuters: Marko Djurica)Mr Zelenskyy said a three-year-old boy was among the dead after the strike on a village outside Kyiv."Four more people were hospitalised: the child's parents, his 15-year-old brother, and a neighbour who came to the family's aid and was wounded in a double-tap strike," Mr Zelenskyy said in a post to X.In its daily report, Ukraine’s air force said it had downed or intercepted 135 of 151 drones launched by Russia overnight. The attack also involved six ballistic missiles and other guided missiles.Meanwhile, Russia's Defence Ministry said on Saturday it continued strikes on Ukrainian port infrastructure and vessels supporting the Ukrainian military.The ministry said Russian forces used precision air-launched weapons and attack drones to hit military warehouses containing communications and electronic warfare equipment in the Black Sea port of Odesa.In the port of Mykolaiv, Russian forces struck a cargo vessel carrying military equipment and a warehouse storing weapons and military supplies, the ministry said. It added that another dry cargo vessel transporting military supplies for Ukraine's armed forces was hit in the Black Sea.Local Russian officials also said six people were injured when a fire broke out at the Ilsky Oil Refinery in the southern Krasnodar region, due to debris from a falling drone, local officials said.Ukraine's General Staff said Ukrainian forces struck the refinery in Krasnodar, along with the Syzran Oil Refinery in the Samara region, more than 800 kilometres inside Russia.ABC/wires