Cannes (France) (AFP) - A "devastating" film about the massacre of an extended Palestinian family in Gaza by Israeli forces in 2009 has been hailed by critics at the Cannes film festival.

Italian filmmaker Stefano Savona spent nine years trying to piece together what happened when a farming community in the north of the Gaza Strip was razed by Israeli special forces, killing 29 civilians mostly huddled together in one house.

The wounded -- largely women and children -- were left for three days before the Red Cross could get to them.

"Samouni Road", which uses animation and 3D images to reconstruct what happened and "bring alive the ghosts" of the victims, has had rave reviews, with one critic calling it "an anti-war film for the ages".

The Hollywood Reporter said "its success at showing real lives unfathomably impacted by barbarism is beyond dispute; the accolades sure to accrue will drown out the few but noisy voices from all sides unable to see beyond their own fanatical propaganda".

The film's premiere comes as 60 people were killed after Israeli troops fired on protesters in the worst violence in the Gaza Strip since the 2014 war, with at least 1,200 other Palestinians wounded.

Savona told AFP that his film was not "reportage or propaganda" but an examination of "the pain and resilience of these people" trying to rebuild their lives after the 2009 massacre.

The Samouni clan have farmed their fields in northern Gaza since time immemorial, Savona said.

- Pilot refused to bomb survivors -

"They consider themselves the original Gazans. They were kind of snobbish about that. They are like a separate community within Gaza, who marry among themselves and have their own dialect.

"They were much less politically involved than most Gazans who are refugees," who settled in the Strip after fleeing or being expelled from their homes in what is now Israel.

"And all the Samounis were against Hamas," Savona added.

Yet their land, homes and mosque were levelled during a massive Israeli "anti-terrorist operation" that the director said turned their community into a "man-made desert, like the moon".

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Savona had been in Gaza at the time, shooting his award-winning documentary "Cast Lead" -- the name given to the Israeli military incursion. He befriended the Samounis when they were allowed back to the ruins of their homes a fortnight after the killings.

"The bodies were in the bombed house for 14 days. I went there every day. People were coming back every morning to go through the rubble and I would talk to them," he told AFP.

"There were 150 people in the house, all cousins, when it was bombarded by an Apache helicopter gunship."

Ironically the Israeli pilot who killed them emerges as a kind of tarnished hero from the film for repeatedly refusing orders to fire on the survivors.

Savona used the Red Cross, UN and the Israeli army's own internal reports on the tragedy. "All that we see and hear comes from cross-checked sources," he said.

"The situation of Gaza was tragic 25 years ago," he told AFP. "Now it has gotten even worse. I just wanted to show these people and let them talk for themselves."

- Red carpet protest -

With the blockade, "Gaza has become this dark place on the map -- a terra incognita -- of which we hear and see almost nothing," said the Sicilian.

He was smuggled into the strip through the tunnels from Egypt when he returned to see the family in 2010, a route he said was now "almost impossible".

"We see almost nothing of life there now. All we see is smoke and fire and small figures running from being shot...

"But we have a responsibility to cover what is happening. If we had told this story in a better way we might have helped, but we haven't," Savona said.

"I did not want to get kidnapped by my own emotions in this film. Thousands of movies end up as psychological blackmail," said the director, who refused to comment on the killings in Gaza this week.

He sees his role as to simply observe, as in his documentary on the Egyptian revolution, "Tahrir, Liberation Square".

However, several stars and directors including Benicio Del Toro and French actress Virginie Ledoyen took part in a minute's silence outside the Palestinian pavilion at the festival on Tuesday to express their horror at what was happening in Gaza.

French-Lebanese actress Manal Issa later staged a protest on the red carpet before the screening of the latest Star Wars spin-off, "Solo", holding up a placard, "Stop the Attack on Gaza".

Issa is the star of the Syrian film "My Favourite Fabric", one of the pictures in the running for the Camera d'Or prize for best debut feature at Cannes.