The directors of seven European film festivals shared the stage at the opening of the 77th Venice film festival to help kick-start an industry that they said was in danger of being usurped by streaming sites such as Netflix because of the Covid-19 pandemic.

Venice head Alberto Barbera said film festivals might have a “reduced role” after the pandemic, which caused every major festival to cancel or offer a hybrid of online and physical screenings.

Barbera said: “The feeling of watching a film on the large screen with other people is in the very nature of the film industry. We have to support cinemas. Many are still closed today, others will never open again.”

The director added that the fight to reopen cinemas and get film festivals back in a physical form was a “battle for civilisation and for culture”. His statements were supported by a letter signed by the directors of seven other film festivals, including Thierry Frémaux of Cannes, and José Luis Rebordinos (San Sebastián) and Tricia Tuttle (London), who will both host physical festivals later this year.

Barbera said that the Covid-19 pandemic had given streaming sites the upper hand in the battle for viewers, and that Netflix’s increasing subscriber numbers coupled with the permanent closure of cinemas could be fatal unless the industry showed solidarity.

Frémaux, who was appearing on the stage of an event that has been Cannes’ biggest rival in recent years, added that festivals were able to give the industry a “positive thrust”, and that cinema at large needed that support now.

He also warned of the ascendancy of what he called “TV platforms” during the coronavirus outbreak and said that streamers and physical cinemas and festivals needed to find a way to co-exist. He pointed to Marvel’s Avengers series as an example of films that worked both as a box-office hit and as a popular streaming option when Disney+ launched last year.

Barbera was in defiant mood at the start of the festival, which is his last in charge and is taking place as Covid infections are rising again in Europe. He has defended his decision to host the event even though every other major festival has either cancelled or is hosting virtual screenings this year.

As the festival opened, there were queues at nine thermo-scanners placed at entrances to the festival site on the Lido, and anyone with a temperature above 37.5°C was being denied entry. Face masks are mandatory at this year’s event, and other safety measures include socially distanced screenings and a tracking system for attendees.

On Wednesday evening, Barbera, along with other festival directors including Carlo Chatrian (Berlin), will officially open the festival with a statement that bills the event as a show of solidarity with the film industry.

The directors will insist that festivals are “not mere promotional showcases”, but are increasingly becoming “centres of culture”, and “opportunities for the cultural enlightenment of audiences and for education to beauty and to the richness of the film experience for young people”.

Along with the release of Christopher Nolan’s Tenet, which was the first major film to screen since lockdown measures closed cinemas around the world, the Venice event has now become a touchstone for an industry desperate to recovery.

The event, which during Barbera’s tenure has become a rival to Cannes as Europe’s most significant film festival, has fewer stars than usual with Cate Blanchett, Tilda Swinton, Matt Dillon and Ludivine Sagnier among international talent expected to attend.

This year’s event has a strong UK contingent as Hollywood names – for the most part – stay away, and Venice looks closer to home for film-makers, jury members and actors. Tilda Swinton is being given a lifetime achievement award and stars in Pedro Almodóvar’s 30-minute film The Human Voice, while The Souvenir director, Joanna Hogg, is part of the Golden Lion jury.

Documentarian Luke Holland has a posthumous screening of Final Account, his film about the rise of the Third Reich, while The Crown star Vanessa Kirby has two films at the festival – Kornél Mundruczó’s Pieces of a Woman and Mona Fastvold’s The World to Come. British actor Kingsley Ben-Adir plays Malcolm X in Regina King’s directorial debut One Night in Miami, an adaptation of Kemp Powers’s play which was at the Donmar Warehouse in 2016, and is a fictionalised account of the night Cassius Clay (then about to change his name to Muhammad Ali) beat Sonny Liston while surrounded by friends including Malcolm X, Sam Cooke and Jim Brown.

The Venice film festival opens on Wednesday and continues until 12 September.