By Allyn Fisher-Ilan
JERUSALEM (Reuters) - Israel threatened illegal immigrants with unlimited detention on Tuesday as it tightened legislation to stop an increasing number of people crossing its porous Sinai Desert border from Egypt.
The move, which raised the maximum detention from 60 days, drew sharp criticism from refugee groups and activists, who said the "immoral" decision would hit refugees fleeing conflict.
The issue of immigration raises fierce emotions in Israel, many of whose citizens themselves arrived as refugees after World War Two's Nazi Holocaust.
Israel's parliament voted through the changes in an overnight session to "handle a situation of infiltrations along the southern border which many view as a plague," said lawmaker Amnon Cohen from the religious Shas party in parliament.
The measure amended a 1954 wartime law which defined infiltrators as guerrillas entering from Egypt to attack Israeli border towns.
Israel may now detain anyone illegally crossing the border for an indefinite period, though an administrative judge must review the case after seven days, and again after three years, the amended law says.
An initial statement from Parliament suggested a three year maximum detention, but a text released later showed no clear limit for incarceration had been set, though every migrant's case would be subject to periodic reviews.
The amendment also gave authorities the power to jail anyone who helps migrants enter illegally.
A record number of migrants, largely from Sudan and Eritrea, have arrived in Israel in the past two years.
Numbers have risen in the past few months, with government figures showing more than 2,000 arrivals across the Egyptian border in November.
That brought the total number of migrants in the country to 51,000, up from 33,000 at the close of 2010.
Israeli ministers have said the vast majority of migrants come to find work, not flee prosecution.
"These are not refugees but people who seek to improve their standard of living at our expense," said cabinet minister Matan Vilnai, calling the migrants "a real threat to the State of Israel," whose Jewish-majority population is 7.5 million.
"DEEP STAIN ON OUR DEMOCRACY"
Aid groups have said more migrants were trying to get into Israel because routes across Libya to Europe had been blocked by the uprising there. Unrest in Egypt may have spurred more refugees to head toward Israel, they add.
"Not only are these steps by the government immoral, they do not provide any solution to the issue of asylum-seekers in Israel," said Yael Marom, coordinator for a Tel Aviv-based aid group called ASSAF.
Moshe Negbi, Israel Radio's legal commentator, called the measure a "deep stain on our democracy."
Israeli cabinet secretary Zvi Hauser told Israeli media migrants were a strain on Israel's society and social services whose infrastructure he saw as "at risk of collapse."
Prime Minister Benjamin Netanyahu's government approved $167 million last month for a planned detention facility for illegal migrants and other measures.
Israel is also building a fence along its frontier with Egypt to try to block the migrants as well as prevent infiltrations by Islamist militants blamed for an attack in August in which eight Israelis and five Egyptians were killed.
(Writing by Allyn Fisher-Ilan. Editing by Douglas Hamilton and David Stamp)