Lizzy Hawker won the women's title in last year's UTMB. Photo: Chiara Dendena

This year’s gruelling Ultra-Tour du Mont Blanc will take place wholly in France.

Difficult weather conditions high on some of the Alpine passes forced organisers to alter the route to avoid some areas, meaning runners will not pass through Italy and Switzerland as in previous years.

The course has been shortened as a result to 100km, and the new route will entail about 6,000m of ascent.

The North-Face sponsored Ultra-Tour will start about 7pm local time today.

Organisers said conditions on the Col du Bonhomme, Col de la Seigne and Grand Col Ferret were too difficult to run the race over.

They said: “The first part of the course remains unchanged to La Balme. Then, it will back to Les Contamines and Les Houches by a different path.

“It will go through the Valley of Chamonix and just before the Col des Montets heading to the CCC course to go back to Chamonix by Argentière.”

Briton Lizzy Hawker will be looking to repeat her women’s’ win of last year and fellow UK runner Jez Bragg, winner of this year’s Fellsman for a second year running, will be looking to improve on last year’s disappointing race when he pulled out after a chest infection affected his breathing.

First racers in the UTMB are now expected back in Chamonix about 5.30am tomorrow, local time.