A mass die-off of fish in Greece's port of Volos has raised a massive stink and led to the country declaring a state of emergency.

The deaths are believed to be linked to climate change after historic storms and flooding washed the freshwater animals out to sea.

Authorities in central Greece told the New York Times that they had dredged more than 100 tons of dead fish from the waters around the scenic summer destination.

Visuals doing rounds on social media show a silvery blanket of dead fish that formed off the port last week.