"Why would you kill someone and decimate an entire family just because she was taking photos?" she told AFP before the screening.

With Israel banning foreign media from entering the besieged Palestinian territory, Farsi reached out to Hassouna through video calls, turning more than 200 days of conversations into "Put Your Soul on Your Hand and Walk".

A day after Hassouna was told it had been selected for a sidebar section at the world's most prestigious film festival, an Israeli missile pummelled her home in northern Gaza, killing her and 10 relatives.

Israel has claimed it was targeting Palestinian Islamist militant group Hamas.

But "they were normal people. Her father was a taxi driver, she was a photographer, her sister was a painter and her little brother was 10 years old", said Farsi.

"My heart goes out to her mother, who lost six of her children, her husband and her home. She lost everything."

- 'Reality caught up with us' -

Tens of thousands of people have been killed in Gaza, while Israeli leaders have expressed a desire to empty the territory of its inhabitants as part of the war sparked by Hamas's October 7, 2023 attack on Israel.

As the death toll mounts, with rescuers saying 94 people have been killed in Israeli strikes so far on Thursday alone, the conflict has cast a shadow over Cannes.

Several actors have walked its red carpet wearing Palestinian flags pinned to their jackets, while others have sported a yellow ribbon for Israeli hostages still held in Gaza.

Exiled Gazans Arab and Tarzan Nasser will on Monday screen "Once Upon a Time in Gaza", a portrait of two friends set in 2007, the year Hamas started tightening its grip on the territory.

On the eve of the festival, "Schindler's List" actor Ralph Fiennes and Hollywood star Richard Gere were among more than 380 figures to slam what they see as silence over "genocide" in Gaza.

"The English Patient" actor Juliette Binoche, who heads the main competition jury, paid homage to Hassouna on opening night.

Sepideh said she had believed until the very end that Hassouna "would survive, that she would come, that the war would stop.

"But reality caught up with us," she said.

Reporters Without Borders estimates around 200 journalists have been killed in 18 months of Israeli strikes on Gaza.