African migrants walk on a road after abandoning a detention facility which began operating last week in the southern Israeli desert Dec. 15. Ariel Schalit/AP

More than 100 African migrants have abandoned an "open" Israeli detention center to march to Jerusalem in protest against a new law allowing their open-ended detention, activists said on Monday.

Many migrants say they are fleeing persecution, forced military conscription or dictatorship in war-torn parts of Africa including Darfur. Israel views the migrants as illegal job seekers and a threat to the Jewish character of the state.

Most of the migrants had already been imprisoned for one to two years without trial, Israeli media reported, when they were transferred over the weekend to the Holot (Dunes) detention center.

One of the detainees on the march, Mubarak Ali, told Israel Radio, "We want them to know that we are still in a prison ... (although) they call it open detention."

The center in southern Israel was opened Thursday after parliamentary approval of a law allowing the open-ended detention of African migrants until their asylum requests, deportation, or voluntary repatriation are completed.

The law would see migrants, now living illegally in Israeli cities, moved to detention centers like the facility in the southern desert.

African migrants caught entering Israel illegally could be jailed in a standard prison for up to one year without charges, according to the new law.

After the law was passed, Interior Minister Gideon Saar said it would "allow us to keep illegals away from our cities."

As the sun set Monday, activists reported that the migrants were making good progress on their walk to Jerusalem and were expected to arrive Tuesday.

Cheska Katz, of Israeli rights group the Hotline for Refugees and Migrants (HRM), said that 135 men, mostly from Sudan, decided not to return to the center Sunday night and instead set out for Jerusalem, about 45 miles away.

"They aren't trying to elude the authorities. Their aim is to reach the Knesset (parliament) and ask for their freedom and to be recognized as refugees," the activist, who is taking part in the march, said by telephone.