In Switzerland, they take their documentaries very seriously. The films are frequently seen in cinemas and are given the respect accorded elsewhere to fictional features.

This explains why Visions du Reel in Nyon (April 23-29), Switzerland’s main showcase for documentaries, is becoming one of the leading events of its kind in Europe.

It is one of a number of documentary festivals that have been aggressively courting sales agents and distributors. It has its own international market, Doc Outlook, with pitching events and market screenings. For all its growing size (along with Locarno it is one of Switzerland’s two key international film events), Nyon faces a battle for industry attention with events such as International Documentary Festival Amsterdam (Idfa) and Sheffield Doc/Fest.

Gabriela Bussmann, head of international relations, concedes it has been a struggle to attract the top UK commissioning editors from the BBC and Channel 4, but other big-name European commissioners will be in town.

“We are not the biggest festival but we have the reputation for having the highest quality of programming,” she says. “Buyers are very curious to know what we’re screening.”

She adds that the Pitching du Reel event is a unique chance to pitch feature documentaries. Among the participants this year will be acclaimed UK director Gideon Koppel, who will be in town to launch a project about writer Paul Celan.

Meanwhile, through Doc Alliance - its collaboration with sister festivals CPH: DOX Copenhagen, DOK Leipzig, Idff Jihlava and Planete Doc Review - Visions du Reel has increasing distribution muscle of its own. Certain films are screened at all five festivals and DocAlliance launched its own online portal in March with 250 films available to be streamed or downloaded.

“Our job is to be an international platform. That means having a strong network,” says the festival’s director, Jean Perret.

This year’s main competition features 20 films from 16 countries. Highlights include Peter Mettler’s Aerial Perspectives On The Alberta Tar Sands (Canada), Thomas Heise’s Material (Germany) and Peter Liechti’s The Sound Of Insects - Record Of A Mummy (Switzerland).

This year marks the 40th anniversary of the Nyon Film Festival, and the 15th since it was renamed Visions du Reel. Film-makers from around the world have been invited to celebrate the twin anniversaries by making ‘haikus’, short films comprising three shots and running up to two minutes. Fred Wiseman, Molly Dineen and other documentary luminaries have contributed.

While insisting the festival is a big-screen event, Perret says Visions du Reel encourages crossover between television and cinema. “(Documentary) producers and film-makers need television to find money and be aired. At the same time, television needs deeply these independent film-makers. We have to work together.”