As a fierce blizzard sweeps mountains outside Teheran, a team of elite Swiss ski instructors refuses to allow the deep freeze to stand in the way of warming ties with Iran.

"The conditions are ... interesting," laughed Vincent Pilet, a member of the Swiss team, as snow whipped sideways into the window of the cafe in Darbandsar resort, a two-hour drive from the Iranian capital.

He said he could handle the weather - the bigger challenge was dealing with the huge numbers of Iranians who had shown up to be tested by the visitors from Switzerland.

Pilet and two other instructors were on a two-week mission, scouting for the best skiers in Iran to train as instructors.

They've been inundated.

"We expected to have maybe 30 to 40 per day, and we've ended up with more like 70, or even 140 on one day," said Loris Ambresin, another member of the Swiss team.

Iran is perhaps not an obvious destination for skiers. But the Alborz mountains above Teheran are home to a clutch of excellent pistes, even if some of the pre-revolution facilities look somewhat dated.

"The chairlifts are a bit old but that just adds to the charm," said Pilet.

Skiing in Iran dates back around 80 years when Germans arrived to dig coal mines in the mountains.

"The people of the village began carving skis out of tree trunks," said Morteza Saveh Shemshaki, head of education for the Iranian Ski Federation.

Resorts popped up and attracted international investors - at one point in the 1970s, a French-made cable car from northern Teheran was the longest in the world.

Although the Islamic revolution of 1979 put the industry on ice, skiing has made a comeback. Whereas the pistes were until the mid-1990s divided by a long rope to segregate the sexes, now everyone can ski together, although some controls remain.

Some "don't like the idea that men and women are having fun together, but there's not much they can do about it up here", said one skier, asking not be named.

When international business ties were rekindled by the 2015 nuclear deal between Teheran and world powers, easing sanctions on Iran, one Swiss firm spotted an opportunity.

Andrea Gabus, who heads the investment company SGCH, believes that building a cadre of world-class instructors will attract more skiers and ultimately more business.

"It's currently an elite sport in Iran, but because of the closeness of Teheran to the resorts, there is the potential to make it more democratic and bring it to more than just one social class," he said.