By Allyn Fisher-IlanHOLOT, Israel (Reuters) - A compound of one-storey buildings deep in the southern Israeli desert is now home to some 400 African migrants who face the prospect of being held in custody indefinitely.The detainees in what the authorities call an "open" detention centre are allowed to leave for a few hours each day, but given its remote location near the Egyptian frontier, travel is impractical.Israel opened the Holot complex in December after its Supreme Court stopped the practice of jailing illegal migrants for up to three years in regular prisons.But in what the migrants call a cruel twist and rights groups say is a rights violation, a law passed the same month allows the migrants to be detained indefinitely, pending the resolution of their requests to stay in Israel."I went to renew my visa, and suddenly I wound up here.