French actress Catherine Deneuve. AFP
The petition began circulating during the buildup to the Cannes film festival and had garnered around 380 names including "Schindler's List" star Ralph Fiennes when the event kicked off on May 13.
An update issued by organisers Friday included more than 900 names, including Deneuve, British director Danny Boyle and Swedish actor Gustaf Skarsgard.
The initiative, called "Artists for Fatem", was sparked by the killing of Palestinian photojournalist Fatima ("Fatem") Hassouna, who was the subject of a documentary that premiered at Cannes week.
Hassouna, 25, was killed in an Israeli air strike along with 10 relatives in her family home in northern Gaza last month, the day after the documentary was announced as part of the ACID Cannes selection.
"As artists and cultural players, we cannot remain silent while genocide is taking place in Gaza and this unspeakable news is hitting our communities hard," the open letter says.
Other signatories include Juliette Binoche, who is chairing the jury at Cannes, Rooney Mara, Jonathan Glazer, US indie director Jim Jarmusch, "Lupin" star Omar Sy, Richard Gere, Susan Sarandon, Pedro Almodovar and Mark Ruffalo.
Wikileaks founder Julian Assange, who is in Cannes to promote a documentary about his life, has also signed the letter, organisers said Friday.
He posed for photographers on Tuesday with a T-shirt bearing the names of killed Gaza children.
On Thursday, Gaza's health ministry said at least 3,613 people had been killed in the territory since Israel resumed strikes on 18 March, unilaterally ending a two-month ceasefire in its war on Gaza.
This brings the total death toll to 53,762. However, the Gaza government media office's updated toll now stands at more than 61,700, as it includes thousands still trapped under rubble and presumed dead.
Israel's relentless bombardment also comes amid a deepening humanitarian crisis, with its blockade of Gaza entering its third month, preventing vital aid from reaching the strip and exacerbating shortages of food, medicine, and basic supplies.
*This story was edited by Ahram Online.
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