The drone incidents in Europe have ignited fears that Moscow’s war on Kyiv is now entangling NATO nations.

A drone has exploded in Bulgaria near the Trans-Balkan gas pipeline, the latest in a surge of unidentified unmanned aerial vehicles entering European territory as regional tensions escalate due to Russia’s ongoing war in Ukraine.

Bulgarian Prime Minister Rumen Radev said on Saturday the drone exploded near the Romanian border and the gas pipeline, which links Turkiye to Ukraine.

“The drone exploded in the immediate vicinity of the Kardam border crossing with Romania,” he said in a video released by the government, noting that it took place about a kilometre (0.62 miles) from the Trans-Balkan gas pipeline’s compressor station.

“There were no casualties,” Radev added.

Separately, a spokesperson for Germany’s armed forces said on Saturday that two drones were spotted at about 10pm (20:00 GMT) on Thursday at a military base in Mechernich in the state of North Rhine-Westphalia, some 35km (22 miles) from the Belgian border.

The spokesperson said military personnel have since been deployed to the spot and added that German police are also investigating.

German media have reported that the Bundeswehr site in Mechernich has a high-security underground storage facility for equipment and spare parts for military hardware and is a base for personnel responsible for the maintenance of US Patriot air defence systems.

A drone was also discovered late on Tuesday at Leipzig/Halle Airport, a civilian freight and NATO logistics hub. It was found near several Ukrainian Antonov An-124 cargo airplanes, according to German media reports.

The drone incidents across the continent have revived concerns about Moscow’s war on Ukraine entangling neighbouring NATO states.

It has also intensified debate about whether strategic members of the military alliance such as Germany are ready to cope with new security threats.

German government officials have not blamed any foreign countries publicly for this week’s drone incidents, but some politicians have accused Russia, which has been at war with Ukraine since its military invasion of the country in 2022.

NATO and European Union officials have, however, blamed Russia for past drone sightings.

In July, after a suspected Russian drone was spotted over NATO member Romania’s airspace, the European Commission said it showed Russia’s war had “crossed yet another line”.

NATO chief Mark Rutte has said Moscow’s “reckless behaviour is a danger to us all”. United States ambassador to NATO, Matthew Whitaker, has pledged the alliance will “defend every inch” of its territory.

Russia has rejected such claims.

On Friday, the Russian embassy in Berlin dismissed the Leipzig event as a “fabricated provocation”, saying it was another example of accusations against Russia without evidence.