More participants in this year's Yukon Arctic Ultra have scratched than finished the extreme marathon race because of difficult situations on the trail.

A total of 49 athletes from around the world had signed up for the Ultra, in which participants run, ski or cycle along the Yukon Quest trail. The event started Feb. 15, one day after the Quest, from Whitehorse.

Some have already completed a standard marathon or a 100-mile [161-kilometre] race along the trail.

But 12 of the 14 competitors who tried to run the more gruelling 300-mile [483-kilometre] event have dropped out midway through the race. One competitor did not even start.

At a hotel in Whitehorse, Francis Beauvallet of France told CBC News he encountered extreme conditions on the trail.

Speaking in French, Beauvallet said he spent 27 hours running alone, without seeing anyone else. He also ran out of water, and his head lamp stopped working.

Knee-deep in snow, he had no snowshoes, he added. So Beauvallet scratched at the McCabe Creek checkpoint, where two fellow competitors also dropped out.

Yukon Arctic Ultra organizer Robert Pollhammer said this year's race has been plagued by a lot of problems.

"It's a strange year, to be honest with you. I mean, we've had the ideal conditions, but there were a lot of people scratching for various reasons," he said Tuesday.

"We had more snow then ever during the race, which caused problems for us. And it's been hard for the staff because the roads we have to travel are very slippery, so yesterday we've had two accidents. Nobody hurt, but still … every year is different.

Meanwhile, about 10 of the 16 competitors in the Yukon Arctic Ultra's most extreme category, the 430-mile [692-kilometre] race, are still in the running.

Mountain cyclist Alan Sheldon of England was the first to cross the finish line in Dawson City, Yukon, on Monday. Enrico Ghidoni of Italy and American runner Bruce Thompson, both runners, arrived on Tuesday.

Pollhammer said he believes this year's Yukon Arctic Ultra is living up to its reputation as the most difficult foot race in the world.