The International Organization for Migration says a 60-car train carrying 1,400 refugees has left Sudan's capital for the newly independent south. The passengers are the first of hundreds of thousands expected to make the arduous journey in the months ahead.

Millions of southerners fled to northern Sudan during the 22-year war that led to South Sudan's declaration of independence in July of last year.

Khartoum ruled after negotiations with South Sudan that all southerners living illegally in the north _ an estimated 500,000 _ would either regularize their status or depart for the south by April 8.

The IOM said Friday that the 1,400 left on Thursday. The journey of over 600 miles (1,000 kilometers) across desert and savannah is expected to take them 10 days.