TEL AVIV  About 1,000 African migrants trying to cross the Sinai Desert from Egypt into Israel have been systematically beaten, raped and held captive for ransom in the past year by the Bedouin smugglers they hired to help them make the journey, an Israeli advocacy organization said Tuesday.

Testimony collected by the Hotline for Migrant Workers in a new report depicts a network of torture camps in the northern reaches of the desert where the migrants, mostly Eritrean, are sometimes held for months in abusive conditions, while their Bedouin captors press their families abroad to send thousands of dollars in ransom money.

“I was a virgin when I arrived in the desert,” said a 21-year-old Eritrean woman cited in the report, who was held for six months. “During the first few times that I was raped, I cried and resisted, but that didn’t help. They wouldn’t leave me alone. After that I stopped resisting. Only when the $2,800 arrived did the smugglers unchain me.”

In their accounts in the report and in person, the migrants recall a pattern of abuse, including gang rapes and beatings with electric rods and heavy sticks. Often, they said, they were shackled together in groups as their armed captors kept them under guard. At one of the camps, captives were given T-shirts with numbers printed on them and were referred to by those numbers.