(Reuters) - Hrity spent three months chained to half a dozen people on a basement floor, beaten with sticks and chains that gave off electric shocks, on a ration of just a spoonful of rice a day.

Now in Israel, the 26-year-old migrant from Eritrea said she was freed only after a $30,000 ransom was delivered in cash to Israeli accomplices of her Bedouin Arab captors.

"I can´t believe I survived it all. I still feel very weak and dizzy just standing sometimes," she said, telling the story of her captivity and journey across Egypt´s Sinai desert, translated by her cousin Teklezghi, also a migrant in Israel, who borrowed from her parents and friends to pay for her freedom.

Some 60,000 African migrants fleeing authoritarian rule in Eritrea and fighting in neighboring Sudan and what is now South Sudan have crossed illegally into Israel across the relatively porous desert border with Egypt.

Half of them arrived in the past two years - more than 3,500 since January alone - and growing numbers of homeless migrants are camped out in Israeli city parks. Prime Minister Benjamin Netanyahu has vowed "to stop this flood we are all witnessing".

Hrity is settled for the moment with Teklezghi in rented quarters in Jerusalem´s walled Old City, but her flight for safety may not be over.

The influx of African migrants has fed into a larger Israeli concern about maintaining a Jewish majority population, an issue which has led to policies that limit eligibility for citizenship in Israel. Jewish immigrants are automatically given citizenship but that option is not open to most African migrants.

Some of the thousands of laborers imported from Asia and Latin America to work in the agriculture sector or caring for the elderly and infirm have also been denied permanent residence or citizenship, even for family members born in Israel.

Since January, Israeli law has been amended further to punish migrants caught entering illegally with up to three years in jail. A detention centre near the Egyptian border is being enlarged to accommodate thousands more inmates.

"These people aren´t refugees, they are first and foremost infiltrators to Israel," said Yossi Edelstein, a senior Interior Ministry official, reflecting Israel´s official view.

"INFILTRATORS"

Israel is not the first choice of destinations for many African migrants. Most head to the country because it can be reached overland and because European countries have become more strict about letting asylum-seekers in, Edelstein said in an interview.

The recent fighting in Libya and cases of treacherous seas claiming African victims travelling on rickety boats have exacerbated the situation and encouraged even more to flee toward Egypt and finally wind up in Israel.

Israeli humanitarian aid groups, some with help from local authorities and the U.N. refugee agency, UNHCR, have opened soup kitchens and shelters to accommodate the most dire cases, especially women with infants and small children.

"We are on the verge of collapse from the demand," said Tamar Schwartz, director of Mesila, a Tel Aviv aid group.

Physicians for Human Rights operates a clinic in the southern reaches of Tel Aviv where many migrants congregate. Many migrant women seek abortions after having been raped during their trek, and some are treated for gunshot wounds suffered on their journeys, officials at the clinic said.

Edelstein said Israel was trying to stop the illegal influx -- a fortified fence is under construction along its Sinai border with Egypt to keep out the migrants as well as armed infiltrators -- and says it is trying to find places where African migrants could be deported safely.

So far about 1,000 Sudanese, offered $1,000 apiece, have agreed to leave Israel voluntarily, Edelstein said.

Israel had planned to seek the repatriation of some hundreds of South Sudanese, but may put those plans on hold given the latest fighting between that country and neighboring Sudan, with whom it split just last year.

In response to legal challenges from human rights groups, the Israeli government has pledged to its Supreme Court that it will not punish employers who hire African migrants. The promise effectively allows the migrants to work, but only on temporary visas, not formal work permits, and only pending further policy decisions.

An Israeli legislative committee session on the issue recently discussed the possibility of Israel permitting migrant workers to replace imported labor from abroad, though immigration officials insist they would not agree to such a move.

Parliament speaker Reuven Rivlin, a member of Netanyahu´s right-wing Likud party, thought Israel had a "sacred obligation" to help displaced people given that it was founded as a haven for Jews after centuries of persecution, minutes of that meeting show.

"We are a people that knows to respect a person fleeing his country for fear of his life," Rivlin said.

But he added the swelling numbers of migrants posed a "strategic" problem for Israel, and urged steps to ensure "these people seeking political asylum are rescued, but that this doesn´t involve a chance for them to seek Israeli citizenship".

LOOKING FOR A WAY OUT

When Hrity left Eritrea in July 2010, she had no clear destination in mind but was vaguely considering Europe.

She travelled to neighboring Sudan, where she paid $1,000 to pay off a gang that threatened her with rape, and then went on to Khartoum. Later she tried to flee to Juba, the capital of South Sudan, but she said Bedouin Arabs abducted her en route and took her to the Sinai.

"I wanted to go to Europe but I was taken to Sinai. I didn´t want to come to Israel," Hrity said in an interview, asking that her last name not be used.

She said she was kept in a basement with other women and children, and that she was sometimes forced along with the other women to undress before being beaten.

During three months in captivity, she was branded with metal rods or tied to a pole, she said. Her captors also beat the bottoms of her feet and forced her to phone her cousin Teklezghi in Jerusalem so he could hear her screams.

Human rights activists in Israel have taken similar testimony from other women migrants.

It took Teklezghi several weeks to raise her ransom. Her parents sold their home in Eritrea for about $10,000 and he borrowed the rest from fellow migrants in Israel.

Israeli police have arrested a suspect who has been identified by Teklezghi and other migrants as the man who took the cash from them so their relatives in Sinai could go free.

The suspect, an Israeli Arab, has since been charged with extorting tens of thousands of dollars in ransom for Hrity and other Eritrean nationals and transferring the money to their captors in Egypt.

Court papers called the suspect a "main link" in a suspected criminal gang also alleged to be based in Palestinian territory.

Several weeks after her experiences, Hrity seems too dazed to think about the future.

She works day jobs, wrapping sandwiches at an eatery and cleaning homes, hoping to make enough money to repay her ransom debt to her family and friends.

"I don´t know how I could ever repay them all, even if I work for 10 years," she said.

(Editing by Jeffrey Heller and Sonya Hepinstall) (© Thomson Reuters 2012. 04/20/12)