A yellow-orange haze smothered several regions after several days of strong winds from the south, limiting visibility and prompting warnings from the authorities of breathing risks.

"It's one of the most serious episodes of dust and sand concentrations from the Sahara since March 21-22, 2018, when the clouds invaded the island of Crete in particular," said Kostas Lagouvardos, weather research director at the Athens Observatory.

Greece had already been struck by Sahara dust clouds in late March and early April that also smothered parts of Switzerland and southern France.

Authorities warn that the dust concentrations can reduce sunlight and visibility while increasing concentrations of fine pollution particles, posing risks for people with underlying health problems.

The Sahara desert releases 60 to 200 million tonnes of mineral dust per year. While the largest particles come rapidly back down to earth, the smallest can travel thousands of kilometres, potentially reaching all of Europe.

The Greek weather service said the skies would begin to clear on Wednesday.