By JOSHUA MITNICK

TEL AVIV—Israel completed the main section of a $416 million fence along the Egyptian border on Wednesday, a project that became more urgent after the fall of President Hosni Mubarak nearly two years ago.

Getty ImagesThis handout image supplied by the Israeli Government Press Office shows a general view of the border security fence along the Israel-Egypt border.

The 144-mile section of the 16-foot-high fence includes barbed wire, surveillance cameras and radar, stretching from the Gaza Strip to just north of Eilat.

Israeli officials said the fence had already stopped the illegal entry of thousands of African migrants and lowered the risk of militant infiltration from the chaotic Sinai Peninsula. An eight-mile section through harder-to-infiltrate mountainous terrain is to be completed this year, a defense official said.

Before construction began 2½ years ago, a few lines of barbed wire on rickety poles protected the border. The porous desert frontier became a threat for Israel after Mr. Mubarak’s fall weakened the security presence on the Egyptian side.

The plan to seal the border was accelerated after a deadly cross-border attack by militants on an Israeli passenger bus and jeep patrol in August 2011.

Israeli Prime Minister Benjamin Netanyahu attended a ceremony with senior army and defense officials on Wednesday to mark the completion of the main part of the project.

Campaigning for re-election, Mr. Netanyahu said the fence was a sign of improved Israeli security. He has called the fence evidence of his efforts to insulate Israel from the turmoil of the Arab Spring revolutions and the influx of mostly Eritrean and Sudanese migrants, which he has portrayed as a national-security threat. The election will be held on Jan. 22.

Some 2,153 African migrants entered Israel illegally in January 2012, according to government data. In December, only 35 entered, according to the data.

“There hasn’t been one infiltrator who has reached an Israeli city in seven months,” Mr. Netanyahu said on the border Wednesday, at a ceremony marking the fence construction.

Israeli security officials say Sinai has increasingly become a haven for militants from the Gaza Strip, local Bedouin tribes and global jihadist groups. Israel is also building a fence on the border with Syria, the prime minister’s office said.

The presence of tens of thousands of African migrants has spurred social tensions in working-class neighborhoods of cities such as Tel Aviv.

Israeli human-rights groups, which say the migrants are seeking asylum from war and oppressive home governments, maintain that Israel has an obligation to admit Africans who reach the border fence.

“If a person asks for asylum on the fence, there is a need to let him in,” said Sigal Rozen, a spokeswoman for the Hotline for Migrant Workers. “Of course, this is not happening.”