Australians returning home from detention in Israel say they were abused, tortured and demeaned while in custody and have asked to meet with the prime minister, Anthony Albanese.

Nine of the 11 Australians who joined more than 400 people from around the world on an aid flotilla to Gaza returned home on Monday, where they were met with hundreds of supporters after landing at Sydney, Melbourne and Brisbane airports.

The activists, who were detained in Israel after its forces began intercepting vessels en route to Gaza on 18 May, were greeted with applause and chants of “free, free Palestine” at the international arrivals gates.

Dressed in grey sweatsuits inscribed with the Israeli prison service logo – though most had crossed the icons out and added missives of support for Palestine – the activists stepped into the arms of their loved ones before sharing their allegations of abuse.

Treatment of Global Sumud Flotilla participants sparked international backlash after Israel’s national security minister, Itamar Ben-Gvir, posted a video of himself taunting detainees as they knelt with their heads on the ground and their hands zip-tied behind their backs.

On Monday the Australian climate activist Violet CoCo alleged she had been detained by Israeli soldiers at gunpoint, stripped of her clothes and pushed into a shipping container where she was beaten, kicked and sexually assaulted before being thrown into a prison yard.

CoCo alleged that soldiers took photos of her naked body, shone the laser sights of their guns across detainees’ faces and denied her access to food, water and a lawyer.

“It was only four days of my life, but it felt like months,” she told Guardian Australia.

“We were constantly kept in a state of different styles of torture, we just didn’t know which pain was coming next. The anticipation of what form their cruelty would manifest was a different type of psychological torture as well.”

Guardian Australia has been unable to verify CoCo’s claims, or similar allegations made by others who landed in Sydney on Monday.

Israel has denied allegations of mistreatment, claiming all prisoners and detainees were held “in accordance with the law”.

The Israeli ambassador to Australia, Hillel Newman, said last week the detained flotilla members were handled with “great sensitivity”. He rejected claims of violence and sexual abuse.

“Out of the 400-plus people that were on the flotilla, no one was harmed,” he told the ABC.

CoCo rejected Israel’s position, pointing to the video Ben-Gvir shared as evidence.

“They released their own propaganda showing [us in the] stress position, showing the violence,” she said.

Newman told the ABC’s 7.30 last week Ben-Gvir’s actions were “disgraceful” and had been “condemned from wall-to-wall” in Israel, including by the prime minister and foreign minister.

CoCo said on Monday she and the other activists had been “utterly failed by our government”.

“I would like Albanese to meet with us, I would like him to look us in the eye and to hear our stories of the abuses that we suffered from Israel, and I would like him to retract our statement that we are a friend of Israel,” she said.

Asked at a press conference on Monday about the activists’ requests for a meeting, Albanese said: “I’m not going to respond without any notice for someone I don’t know, I don’t know their circumstances”.

He said the government had “made its position” on Ben-Gvir’s behaviour “very clear”.

“People are deserving of a level of respect and decency, and that minister’s behaviour and his rhetoric … were not consistent with what I would expect,” he said.

Another activist, Surya McEwan, said he had lost count of the number of times he had been punched and kicked in the face and body, and had suffered a fractured cheekbone, a contusion on his lung and a concussion after his detention.

Neve O’Connor, who was detained by Israel for a second time after taking part in a separate attempt to reach Gaza in April, alleged she was “abused, physically beaten and assaulted”.

Juliet Lamont, who had also been previously detained by Israel, alleged that she, too, was sexually assaulted and beaten, that she had been cable tied and had had so much water thrown in her face that at one point she thought she “was going to drown”.

The Israeli embassy in Canberra did not respond to a request for comment on the specific allegations made by CoCo and others on Monday.

The Greens senator Mehreen Faruqi, who joined the contingent at Sydney airport on Monday along with the independent senator Lidia Thorpe, urged Labor to sanction Israel and cut ties with the country.