Drone views of European river's massive fish kill

STORY: Tonnes of dead fish have been found since late July in the river Oder, which runs through Germany and Poland. Both sides have said they believe a toxic substance is to blame but have yet to identify it.

German broadcaster rbb reported the state laboratory found high levels of mercury in the water samples, but the governor of Poland's Lubusz region said their inspectors had only found trace amounts.

According to Poland's national water management authority, 11 tonnes of dead fish had been recovered from the river on the Polish side by Thursday evening.