A Bulgarian army bomb disposal squad detonated a device connected to a drone that landed on Sunday evening near the Black Sea town of Tyulenovo in a controlled explosion on Monday, according to the defense ministry.

According to the defense ministry, an army detachment investigated the spot and decided that transferring the drone to another position with the explosives still attached would be impossible.

“We can certainly assume it is related to the war that Russia launched against Ukraine,” Defense Minister Todor Tagarev told reporters. “This war will inevitably increase the risks to our security.”

Tagarev did not provide more detailed information on where the drone came from and how it reached NATO member Bulgaria.

The tourist resort of Tyulenovo is situated 70 kilometres (43 miles) south of the Romanian border and across the Black Sea from Crimea, the peninsula annexed by Russia in 2014 and now a regular target of Ukrainian drone attacks.

Police cordoned off the area on Sunday evening and restricted public access to local restaurant terraces, Marian Zhechev, mayor of Shabla municipality of which Tyulenovo is a part, told Nova TV.

He said the drone had been found on rocks next to moored boats at Tyulenovo, describing it as an “aircraft with standard ammunition”.

It was unclear whether the drone had fallen from the air or had been washed up by the sea currents.

Nova.bg web site quoted witnesses as saying that the drone was between 3 and 3.5 metres long.

Last week, fragments of a suspected drone were found in Romania, after a new Russian attack on Ukraine’s Danube ports across the border.