Paul Heslop, head of U.N. Mine Action at the United Nations Development Programme in Ukraine, told reporters in Geneva that PMF-1 mines, also known as “butterfly” mines, were light enough to float downstream for a large distance.

“I would not be surprised to see that those mines have either got down as far as the sea or over the coming months, as the water is continuing to flow, will be transported down there,” he said.

“Unfortunately, we could see anti-personnel pressure mines washing up on beaches around the Black Sea.”

Henslop said anti-tank mines, which are heavier than anti-personnel mines, were less likely to float long distances.

The collapse of the Russian-held dam on June 6 unleashed floodwaters across southern Ukraine and Russian-occupied areas of the Kherson region, killing more than 50 people and destroying homes and farmland.

Ukraine’s environment minister said on Tuesday that the dam’s collapse had caused 1.2 billion euros in damage.

Ukraine accuses Russia of blowing up the Soviet-era dam, which has been under Russian control since the early days of its invasion. The Kremlin has accused Kyiv of sabotaging the hydroelectric facility.

(Reporting by Gabrielle Tétrault-Farber; Editing by Emma Rumney)