JERUSALEM—Haunted since last summer’s war in Gaza by Hamas’ success in infiltrating fighters into Israel through tunnels, Israel announced on Thursday the development of the first effective system for detecting tunneling activity at a distance.

One of Israel’s leading defense electronics firms, Elbit Systems, said the system it developed in conjunction with the Israeli Defense Ministry is based on a series of sensors. Data that they furnish is analyzed by a control system, using algorithms. Terming the system "the first of its kind in the world," the firm said the method enables the precise identification of tunnel building "without false alarms."

During the 50-day-long war, 32 "attack tunnels" built by Hamas were uncovered by Israeli sappers, or combat engineers. All began from built-up areas in Gaza, with most stopping just short of the Israeli border. Some, however, continued under the border fence. On several occasions, Hamas fighters emerged from the tunnels inside Israel wearing Israeli army uniforms and ambushed troops. Some succeeded in escaping back into Gaza.

The greatest fear was that they would penetrate nearby civilian settlements and attempt to seize hostages or stage a massacre. The militants often appeared within a few hundred meters of kibbutzim, but they were halted before reaching them. After the war, a number of border residents decided to move elsewhere in the country for fear of the tunnels.

The new system is already being hailed in the Israeli press as the underground equivalent of Iron Dome, developed in Israel as a response to the rockets fired into Israel by Hamas and by Hezbollah in Lebanon. In the Gaza War, the system interdicted close to 90 percent of the rockets heading for inhabited areas.

Residents of border kibbutzim expressed a measure of relief at the development.

"For us, the tunnel threat registered as insoluble," said Amit Caspi, of Kerem Shalom, the kibbutz most threatened by tunnels, "so if there is a breakthrough here it could really improve personal security, even though we know there is never 100 percent certainty."

Hamas and other militant groups in Gaza succeeded in 2006 in digging an 800-yard-long tunnel under the border near Kibbutz Kerem Shalom and killing two Israeli soldiers and capturing a third, Gilad Shalit. Shalit was exchanged five years later for more than 1,000 Palestinian prisoners. Other cross border tunnels were discovered two years ago packed with explosives, apparently to be exploded under Israeli tanks.

The Israeli army has been looking for a solution to the tunnel threat for a decade and has examined some 700 project proposals, according to a military source. A number of projects were implemented but did not succeed. The threat that manifested itself during last summer’s war focused minds and made budgets available for an intensive search for a breakthrough. Officials said the new project incorporates lessons learned from previous failures.

The estimated cost of constructing the system is $3.5 million per mile. The intention, said officials, is to build the system along the entire 35-mile land border between Gaza and Israel.