Israeli Prime Minister Benjamin Netanyahu announced Sunday that his country would start construction of a border fence with its southern neighbor Egypt.
The project, which will cost $270 million, is designed to prevent the migrants, illegal drugs and Palestinian militants from entering Israel.
Netanyahu said he had "taken the decision to close Israel's southern border to infiltrators and terrorists. This is a strategic decision to secure Israel's Jewish and democratic character."
The two sections that will be completed first are north of the Red Sea city of Eilat and near the Gaza Strip.
In recent years, thousands of immigrants from Africa have made the arduous journey across the Sinai desert in search of freedom from political persecution, and work. Israeli police say more than 100 of these immigrants a week cross into Israel.
The migrants come from Eritrea, Ethiopia and Sudan, and their presence is proving a costly headache for the Israeli authorities, further reducing the Jewish majority inside Israel.
The immigrants' journey is a dangerous one. At least 17 have been shot dead by Egyptian border forces in recent months.
Netanyahu said Israel would remain open to refugees but could not let immigrants "inundate our country."
Israel's northern border with Lebanon and its eastern frontier with Jordan are bounded by sophisticated fences.
Until it signed a peace treaty with Jordan, that border was a regular locus of fighting and incursions, and Hezbollah's control of southern Lebanon made that border a source of constant friction.
Israel and Egypt made peace at Camp David in 1979, and Israeli forces pulled out of the Sinai Peninsula. Since then, the border has been open and the area vulnerable to smuggling.
On Monday, Egyptian sources in Cairo said they had not been informed of the latest plan but would not object as long as the fence was built on Israeli soil.