Tests have shown the presence of toxic hydrocarbons in the River Odra, which are not of natural origin but a technological by-product, two opposition MPs said on Monday in Olsztyn, northern Poland.
With climate change meaning hotter summers and low levels of water in one of Poland's biggest rivers, experts say that it was only a matter of time before something happened.
Donald Tusk, leader of Poland’s main opposition party and a former prime minister, has accused the government of having something “to hide” over the River Odra pollution disaster.
Rare microorganisms known as golden algae found in recent water samples from the River Odra could be the source of the river's contamination, a government minister said on Thursday.
There are no pollutants in the samples taken from drinking water intakes near the River Odra where masses of dead fish have been found, the local authorities in north-western Poland have told PAP.
Poland's Chief Inspectorate of Environmental Protection (GIOS) has sent samples of water from the River Odra to foreign laboratories in order to find out the cause of its pollution.
Mateusz Morawiecki, Poland's prime minister, said on Monday that the government will look for ways to tighten laws against the illegal dumping of waste into rivers while promising harsh punishments for those found guilty.
Large numbers of dead fish were found in the Ner river, in the central Łódzkie province, following a similar incident in the River Odra, which flows through Poland and Germany.
The results of Polish and German tests of water samples taken from the River Odra, where masses of dead fish had been discovered, are the same, Poland's deputy climate and environment minister has said.
Donald Tusk, the leader of Poland's main opposition party Civic Platform, has criticised the government for what he regards as its belated reaction to a pollution spill in the River Odra that has killed tonnes of fish.