Israel began arresting African migrants around the country Sunday, three days after the government announced South Sudanese refugees had a week to leave of their own accord.

Twenty-two migrants were detained by immigration police across the country, mostly in the south.

Among those arrested were eight migrants from South Sudan, three from Nigeria and two from the Ivory Coast. In addition, three migrants from Sri Lanka, two from Romania and two from Moldova were arrested.

Interior Minister Eli Yishai said those who did not register with his ministry would be held. “Those who arrive at our offices will not be arrested. They will have a week to leave the country voluntarily. Those who hide will be arrested,” he said, according to Ynet news.

“They reside in many cities in the country,” said Yishai. “Their expulsion is no simple task…. We’ll find them everywhere.”

About 150 migrants and others held a rally in Tel Aviv’s Levinsky Park against the arrests Sunday afternoon. The park, near the city’s bus station, is home to a large African community.

Israel’s treatment of the migrants has drawn sharp criticism from human right organizations. On Sunday, Human Rights Watch said a newly revised law that punishes asylum seekers for illegally crossing into Israel is in violation of basic human rights.

“The new Prevention of Infiltration Law treats all irregular border-crossers as “infiltrators,” said an HRW press release.