TEL AVIV, Israel (AP) — Thousands of African asylum seekers and their local supporters are protesting against an Israeli plan to deport them.

The Israeli government has given the migrants until April 1 to leave the country for an unnamed African destination in exchange for $3,500 and a plane ticket, or they will be incarcerated indefinitely.

The Africans, nearly all from dictatorial Eritrea and war-torn Sudan, say they feel great appreciation for Israel, coupled with dread over the looming expulsions.

Israel considers the vast majority of the nearly 40,000 migrants to be job seekers and says it has no legal obligation to keep them. Critics have called the government plan unethical and a stain on Israel’s image as a refuge for Jewish migrants.

Organizers say some 15,000 gathered in south Tel Aviv Saturday.