Swiss firefighters on Tuesday battled a forest fire that forced more than 200 people to evacuate and authorities warned the blaze could spread further if winds pick up and take days or weeks to extinguish fully.

Fire broke out on Monday on the forested flank of a mountain in Bitsch in the Valais canton near the Italian border. Helicopters hovered overhead throughout the night to drop water onto the blaze.

Mario Schaller, in charge of firefighting operations, said it could take days or weeks to fully put out the fire, which has spread to 100 hectares of forest.

"No one has been injured so far, no buildings have been damaged," he said.

Although there were large amounts of smoke, the blaze began to die down on Tuesday, but could easily spread if winds pick up again, officials said.

"During the night, the goal was to contain the fire in the area where the villages had been evacuated," said Adrienne Bellwald, spokesperson for the cantonal police.

"Thankfully the wind has subsided ... The situation is calm now, but it could change with the wind."

The Federal Office for the Environment has warned forest fires could become more frequent, especially in summer, due to an increase in hot, dry weather caused by climate change.

The regional police department said an investigation had been opened to determine the cause of the fire.

Large areas of Europe, Asia and the United States are suffering extreme weather and the World Meteorological Organization warned the northern hemisphere heatwave is set to intensify this week.

 

(Reporting by Denis Balibouse; Writing by Gabrielle Tétrault-Farber; Editing by Janet Lawrence)