At least 100 African migrants made their way to Jerusalem under police escort Tuesday morning to protest their detention in a new “open prison” in the south of the country.

The migrants, many of whom are on hunger strike, had fled the Holot facility near Beersheba on Sunday and intended to stage a sit-in outside the Prime Minister’s Office to demonstrate against rules keeping them in the prison.

Police spokesman Micky Rosenfeld said 100 migrants were being bused to Jerusalem with police escorts.

Other media reports put the number of protesting migrants higher.

The migrants spent Monday night in an underground shelter in Kibbutz Nachshon, near Beit Shemesh, where they were bused by volunteers after marching toward the capital for much of the day.

The Sudanese nationals arrived at the Beersheba bus station Sunday with the intention of boarding buses to the capital in order to bring their demands to the Knesset

However, after they were prevented by immigration authority officials from boarding the buses, the migrants hunkered down to spend the night at the bus station with little protection from the biting cold.

One of the migrants collapsed due to the cold and was hospitalized at Soroka Hospital in the city. Two others were also given medical treatment.

Many of those marching are also on hunger strike against their detention, with they began upon arrival at the Holot facility last week.

Holot replaces the Saharonim prison complex, where migrants have been held. The new compound, where the terms of the migrants’ detention are somewhat more lax than at Saharonim, was erected after the Supreme Court ruled that incarcerating the migrants without trial for up to three years, as was previously the standard, was unconstitutional.

MK Dov Khenin (Hadash) said the migrants’ abandonment of the new detention site was to be expected as it was just another prison.

“Without the possibility of working, the people have no reason to stay in such a facility, which is a prison in every sense of the word, except for the ability to leave,” he said, deriding the government’s description of the facility as “open.”

“This incident proves once again that the government hasn’t found real solutions for those seeking shelter,” Khenin added.

Jessica Katz of the Center for Refugees and Migrants went to speak with the Sudanese who had gathered at the bus station.

“They don’t understand the significance of the transfer to the ‘open’ facility, among other things, because many of them claim that last week they were told they were going to be released from Saharonim, and they even underwent interviews ahead of such a release. But after they got on the buses from the prison they understood that they were being taken straight to the new facility,” she said. “They are confused and they don’t know how long they will be held at that facility, which is, in practice, like a prison.”

Since last Thursday when the new Holot site opened, 282 migrants have left the facility and refused to return. Four hundred and eighty African migrants, mostly from Eritrea and Sudan, were transferred to the compound, which is located in the Negev desert and has a capacity of 3,000.

The facility has an open-door policy in which residents are permitted to leave the site during the day but are required to return three times for a roll call. The Holot gates are locked between 10 p.m. and 6 a.m. every night, during which time all residents must be behind its fences. Around a dozen migrants were to be housed in every dorm room, and each wing, with a capacity of 140 residents, has its own dining room and recreation areas.

Last week, in the wake of the court ruling prohibiting the incarceration of migrants without trial for up to three years, the Knesset approved changes in the Migrant Law to enable authorities to imprison migrants who arrived in Israel after June 2013 for up to a year without trial and to keep them indefinitely at the new Holot facility.

There are currently upwards of 50,000 African migrants in Israel. Some 1,750 were being held by the state when Holot opened, most of them at Saharonim.

Stuart Winer and Lazar Berman contributed to this report.