A river in the Balkans, known for its stunning natural beauty, has been transformed into a giant floating rubbish heap, amid a spell of bad weather, worsened by long-running mismanagement.

Tonnes of plastic bottles, rusty barrels, used tires, household appliances, driftwood and other waste have piled up behind a barrier in the Drina River in Bosnia-Herzegovina, which snakes through forested hills.

Much of this rubbish was dumped in poorly regulated riverside landfills or directly into the waterways that flow across three countries in the Balkans, accumulating behind the fencing as it flows downstream.

The barrier installed by a Bosnian hydroelectric plant, a few kilometres upstream from its dam near Visegrad, a city in eastern Bosnia that has unwillingly been turned into a waste site, local environmental activists complain.

Heavy rain and unseasonably warm weather over the past week have caused many waterways in Bosnia, Serbia and Montenegro to overflow, flooding near-by areas and forcing scores of people from their homes.

Dejan Furtula of the environmental group Eko Centar Visegrad said “the huge inflow of garbage” was not stopping, despite torrential rainfall and floods subsiding.