Israeli immigration authorities say they have detained dozens of African migrants as part of a new operation to deport illegal immigrants.

Officials say immigration police arrested at least 55 migrants, mostly South Sudanese, during raids in the southern city of Eilat and parts of central Israel.

Rights activists criticized the raids, saying they create fear among migrant families who worry about returning to dangerous living conditions in their African homelands.

Israeli immigration authorities began the crackdown on Sunday, detaining eight Africans days after a Jerusalem court approved the government's plan to deport an estimated 1,500 South Sudanese who entered Israel illegally. Rights groups had petitioned the court to bar the expulsion.

The Israeli government has called the migrants a threat to the country's Jewish identity and has been building a fence along the border with Egypt to stop the influx.

Around 60,000 Africans have sneaked into Israel across its porous desert border with Egypt since 2005. Many of them have looked for work. Some have requested political asylum.

Israel's parliament passed a law earlier this month designating all people who sneak into the country as “infiltrators” who can be detained prior to deportation.

Israeli Interior Minister Eli Yishai said he would begin enforcing the law against South Sudanese migrants before seeking approval to detain and deport Eritreans and Sudanese.

U.S.-based rights group Human Rights Watch called for the Israeli parliament to repeal the law, saying it punishes asylum seekers and their children in violation of international refugee standards.

In a statement issued Sunday, the group also accused Israeli officials of inciting recent attacks by extremist Jews on African migrant communities. Many Israelis blame the migrants for a series of rapes and other crimes in Tel Aviv and other cities.