Ariel Schalit, File, Associated Press
FILE- In this Aug. 20, 2007 file photo, a Sudanese refugee family sit on the ground surrounded by Israeli army soldiers after they crossed illegally from Egypt into Israel. Israel's parliament on Tuesday, Jan. 10, 2011 approved harsh new penalties on illegal migrants and Israelis who help them, passing one of several controversial measures designed to stanch the flood of Africans seeking sanctuary from poverty and conflict.

JERUSALEM — Israel's parliament on Tuesday approved harsh new penalties on illegal migrants and Israelis who help them, passing one of several controversial measures designed to stanch the flood of Africans seeking sanctuary from poverty and conflict.

The bill makes it possible to imprison illegal migrants for life over property crimes and detain them for up to three years without trial. Anyone caught helping migrants could face prison terms of five to 15 years.

Critics deplore the new law and say it is an unconstitutional trampling of human rights. They accuse the government of failing to formulate a coherent, humane policy on illegal migration that would address an issue that has become increasingly urgent over the years.

Prime Minister Benjamin Netanyahu, who has called the swelling number of illegal migrants a "national scourge," voted for the bill. His spokesman, Mark Regev, called the legislation part of a "multitier strategy to deal with the challenge of illegal immigration to Israel." But he would not comment on critics' concerns about the new law.

Lawmaker Nitzan Horowitz of the dovish Meretz Party called the new law a "stain" on Israel's legal code. In a commentary Monday, retired Judge Boaz Okon, the legal affairs analyst of the Yediot Ahronot newspaper, called it "unlimited license to employ terror against anyone who reaches Israel."

Africans began trickling into Israel through its porous southern border with Egypt's Sinai desert after Egyptian security forces violently quashed a demonstration by a group of Sudanese refugees in 2005, killing at least 20. The number of migrants surged as word spread of safety and job opportunities in the relatively prosperous Jewish state.

The government estimates 50,000 Africans have illegally entered Israel since. The overwhelming majority, officials say, have come in pursuit of a more comfortable life and are not fleeing persecution.

Migrant advocates contend the Africans are bona fide refugees and should be granted asylum. They accuse the government of ignoring the retribution most of the migrants face should they return home.

The influx has touched off a national debate in a country that grew out of the Nazi genocide of Jews. Some Israelis call the migrants an economic and social burden and fear their mounting numbers will dilute Israel's Jewish character.

Others say the Jewish people, because of their history of persecution, must be espeically accommodating of others escaping persecution or conflict.

The Africans have congregated in several cities, but a lack of a coherent government policy has led to the creation of slums and friction with locals who claim the migrants have brought crime and harassment of women.

Israel already has repatriated hundreds of Africans and Netanyahu has said he would explore the possibility of repatriating others when he visits Africa this year.

Last month, the Cabinet voted to finance a $160 million program to finish building a 150-mile (250-kilometer) border fence along the Egyptian border and expand detention facilities to hold thousands of new arrivals. Employers who hire illegal migrants now face stiffened fines of up to $18,000.