The cause of the mass death of fish in the Oder river, that runs through Germand and Poland, is still unknown despite further chemical testing.
Tonnes of dead fish have been removed from the German and Polish waterway since late July. Both countries say a toxic substance is to blame, but have yet to identify it.
Dead fish are removed from the Oder river by the German border, in Krajnik Dolny, Poland./Annegret Hilse/Reuters
Despite Polish and German authorities working "flat-out" to establish the cause behind the mass fish die-off in the river Oder, it is still as of yet uknown.
German Environment Minister Steffi Lemke on Friday, warned of an environmental catastrophe.
"An environmental catastrophe is in the offing," Lemke told the RND newspaper group. "All sides are working flat out to find the reasons for this mass die-out and minimise potential further damage."
Polish authorities plan to set up a barrier on the Oder near the city of Kostrzyn to collect dead fish flowing down the river, with 150 Territorial Defence Forces soldiers delegated to help with the clean-up.
Polish soldiers pictured helping with the river clean-up. /Lisi Niesner/Reuters
On Friday, Polish Prime Minister Mateusz Morawiecki fired the head of Poland's national water management authority, Przemyslaw Daca, and the head of the general environmental inspectorate Michal Mistrzak, saying that their institutions should have reacted earlier.
An analysis of river water taken this week showed evidence of harmful "synthetic chemical substances," the German state of Brandenburg's environment ministry said.