Italian authorities have closed roads and evacuated mountain huts after experts warned that part of a glacier on Mont Blanc could collapse.
Officials said around 250,000 cubic metres of ice are in danger of breaking away from the Planpincieux glacier on the Grandes Jorasses peak, according to officials.
It comes as the mayor of the nearby town of Courmayeur said global warming was changing the mountain.
On Tuesday, Courmayeur Mayor Stefano Miserocchi signed an order to close roads in the Val Ferret on the Italian side of Mont Blanc.
The move came after experts warned that a section of the glacier was sliding at speeds of 50-60cm per day.
Mr Miserocchi told Italian media: "These phenomena once again show how the mountain is going through a period of major change due to climate factors and, therefore, it is particularly vulnerable."
He added that was no threat to residential areas or tourist facilities but mountain huts in the Rochefort area were being evacuated as a precaution.
Experts from the Valle d'Aosta regional government and the Fondazione Montagna Sicura reportedly said it is impossible to predict exactly when the mass of ice would collapse.
Recently the melting of mountain glaciers and the retreat of polar ice sheets has been accelerated by rising global temperatures.
Earlier this month, hundreds took part in a "funeral" ceremony to mark the disappearance of the Pizol glacier in north-east Switzerland.
The Galrus Alps glacier had shrunk to a tiny fraction of its original size with scientists saying it has lost at least 80% of its volume just since 2006.
In August, the Okjokull glacier in Iceland was also commemorated with a plaque as the first of the country's glacier to completely melt after it was officially declared dead five years ago.
Earlier this year tourists on the island captured a section of another glacier, Breiðamerkurjökull, breaking away, which caused a massive wave.
The Mont Blanc massif is Western Europe's highest mountain range.
It has 11 peaks above 4,000m in France and Italy and attracts hundreds of thousands of tourists every year.
