Hundreds of African illegal immigrants on Monday began a protest march to Jerusalem after fleeing a detention centre in the south where they were being held, an AFP correspondent said.
The group, all men, could be seen marching northwards along a highway near Lahav junction in southern Israel, holding up signs reading: "Recognise us as refugees" and "Holot (detention) facility is a prison," the correspondent said.
A spokeswoman for Israel Prisons Service told AFP that 282 inmates who were being held at the Holot detention facility had not shown up for the evening lockdown on Sunday night.
She said they had made their way to Beersheva, more than 50 kilometres (30 miles) away, where they spent the night at the central bus station in freezing wintry conditions.
The sprawling detention facility opened its gates for the first time on Thursday with 484 illegal immigrants from Africa taken there, the IPS said.
It is open during the day but inmates must return for a night lockdown. The centre was initially designed for up to 3,300 people, but can be expanded to hold as many as 11,000.
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Officials said the protesters were likely to be arrested for not returning to the Holot centre.
Speaking to public radio, Israel Population and Immigration Authority head Amnon Ben Ami said they could be arrested 48 hours after failing to show up for the Sunday evening lockdown.
Under legislation passed on December 10, illegal immigrants entering Israel can be held for up to a year without trail.
It was the latest in a series of measures aimed at cracking down on the numbers of Africans entering the country illegally, which Israel says poses a threat to the state's Jewish character.
The new law amends earlier legislation which allowed for immigrants to be held for up to three years without trial that was overturned by the Supreme Court in September.
The Association for Civil Rights in Israel (ACRI) said on Monday that it and other rights groups had filed a petition against the new law.
"The organisations claim that the new amendment does not abide by the principles set forth by the court's September 15 decision to overturn the previous amendment to the law, and is in many ways more severe than the nullified amendment," it said.