Israeli authorities on Sunday began a roundup of South Sudanese migrants ahead of their deportation, three days after a court ruled that their lives were no longer threatened in their homeland.

“The deportation operation is getting under way. We are starting the job,” Interior Minister Eli Yishai told independent television station Channel Two.

“We told the infiltrators from South Sudan to come voluntarily; whoever doesn‘t, with the Lord’s help we shall get them all ... they‘ll be put on a plane,” he said.

The channel reported that eight South Sudanese were taken into custody on Sunday and “would be deported soon.”

The Jerusalem Post quoted the immigration authority as saying that a total of 22 people were arrested on Sunday -- eight South Sudanese, three Nigerians, three Ghanaians, two from Ivory Coast, three Sri Lankans and three Romanians.

News of the swoop sent hundreds of African migrants onto the streets of south Tel Aviv in protest, some calling for the United Nations to intervene on their behalf, Channel Two said.

In video footage of the march they could be heard chanting: “An African is a human being.”

The Post quoted a South Sudanese community worker as saying that his countrymen had expected to have more time to prepare for their departure.

Interior ministry statistics show that approximately 60,000 African immigrants have entered Israel illegally, about 1,500 of whom are from South Sudan with which Israel has friendly relations.

Human Rights Watch on Sunday urged Israel to repeal or amend a law that allows migrants to be detained without charge for up to three years, calling it a violation of “basic rights.”

“Subjecting irregular border-crossers to potential indefinite detention without charge or access to legal representation would violate the prohibition against arbitrary detention under international human rights law,” the New York-based group said.

Israel announced on June 3 that officials would be able to detain migrants who crossed into the Jewish state illegally for up to three years, as part of a bid to stem the flow of African migrants into the country.

But Human Rights Watch said the law stood to stoke anger against migrants, which erupted last month when a protest by around 1,000 people against the rising number of Africans in Israel turned violent.

“Israeli officials are not only adding rhetorical fuel to the xenophobic fire, but they now have a new law that punishes refugees in violation of international law,” said Human Rights Watch’s refugee program director Bill Frelick in a statement.

“The law should be amended immediately, and not enforced until necessary revisions are made.”

In February, the defense ministry announced plans to build an immigrant detention centre in southern Israel at a cost projected at the time of 250 million shekels (about $64 million). (AFP)