The 11 Australians among the 400 flotilla participants detained in international waters by Israel have joined the official submission lodged in The Hague, in the Netherlands.
The wider group of flotilla activists allege they suffered abuse at the hands of Israeli forces, such as broken limbs, sexual assaults, tasers to the face and being injected with unknown substances.
Australian lawyer Bernadette Zaydan, part of the legal team taking evidence to the court, said the communication alleged war crimes, crimes against humanity, torture and other serious violations of international law.
"For the survivors, it is the beginning of hopefully what will be accountability," Ms Zaydan told AAP.
"This isn't just about the violent interception of the Global Sumud Flotilla vessels, it's about the thousands of Palestinians who have lived and died under the same system of abuse, impunity and violence."
The flotilla was attempting to deliver food, medicine and baby formula to the war-torn Gaza Strip.
Israel's bombardment and starvation of the region have killed more than 72,000 people and destroyed the territory's infrastructure, according to the United Nations World Food Program.
The latest mission foregrounded Israel's National Security Minister Itamar Ben-Gvir, who drew widespread condemnation after posting a video of himself taunting detainees as they knelt with their heads on the ground and their hands tied behind their backs.
The video led the Australian government to call in Israel's ambassador and senior ministers to label the behaviour "disgraceful".
But the activists want stronger action and sanctions applied to Israel, as well as an audience with Prime Minister Anthony Albanese.Â
"If Australian survivors can be heard in The Hague but not in Canberra, something has gone badly wrong," flotilla participant Juliet Lamont said.
Lawyers are now collecting evidence, including witness statements and medical examination records, to make a formal submission to the court.
Israel's prison service has denied the abuse allegations.
Lifeline 13 11 14
beyondblue 1300 22 4636
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
13°C