By SAM F. GHATTAS, Associated Press Writer Sam F. Ghattas, Associated Press Writer –  BEIRUT – The Middle East's espionage wars are heating up after Lebanon's arrest of more than a dozen alleged Israeli spies, and dire warnings from Jerusalem that Arab groups are trying to use the Internet to infiltrate the Jewish state.

Officials in Beirut say they struck a strategic blow against Israel with the recent arrests of 15 people — 13 Lebanese and two Palestinians — who they contend were gathering intelligence on Hezbollah positions, leaders' movements and infrastructure targets. Iranian-backed Hezbollah militants and Israeli forces fought an inconclusive war in 2006 along the Lebanese-Israeli border and both sides have since been preparing for the possibility of another.

Although Israel and its Arab neighbors have for years spied on each other, the recent announcements have highlighted the secret war of espionage and the depth of the infiltration. Lebanese officials say the spies arrested there included a math teacher and housewife, and that they were equipped with sophisticated electronics.

Lebanon holds elections June 7 but the recent arrest announcements did not seem intended to influence the vote.

Hezbollah stepped up pressure against the alleged spies, with the group's leader demanding Friday that authorities implement the death penalty against those found guilty of spying for Israel.

In a videotaped message broadcast from a giant screen to tens of thousands of supporters at a rally in southern Lebanon, Hassan Nasrallah asked for "severe punishment for the collaborators and the spies" and "mercy" for their family members.

In Israel, meanwhile, the Shin Bet internal intelligence service this week urged people to be careful when using social networking sites such as Facebook, contending Arab groups are using them to recruit and hire spies. In one instance, Israeli intelligence said an Israeli Facebook user was contacted by a man who introduced himself as a Lebanese agent and offered money for information.

Israeli officials have said Hezbollah has also used the illegal drug trade to lure Israelis into working for them. Over the past decade, two Israeli drug officers and two military trackers were sent to jail for passing information to Lebanese drug dealers.

In 2007, Azmi Bishara, a fiery Israeli Arab lawmaker, fled the country a few weeks before he was accused of relaying sensitive information to Hezbollah during the war. He now lives in Jordan. Since the war, Israel also has accused a handful of Arab citizens of collaborating with enemies in Lebanon.

Israel's government routinely refuses to discuss its intelligence activities, but Israeli commentator Ronen Bergman, a private expert on security affairs, said reports emerging from Lebanon could signal key errors by Israeli intelligence.

Bergman, author of the new book "The Secret War with Iran," said the details of the network being published in the Lebanese media — and the apparent ease of unraveling the operation — "are all signs that are worrisome for Israel."

Added Shlomo Brom, former chief of strategic planning for the Israeli military and an expert on south Lebanon and Syria: "If the Lebanese authorities say they have caught Israeli spies, there's a high likelihood that it's true."

Hezbollah, a Shiite group, doubles as a guerrilla army with a large rocket arsenal pointed at Israel. It is also a political party with lawmakers in Lebanon's parliament and veto power in the current government. The militants have defied international calls to disarm and have the support of the Lebanese government and the military in the conflict with Israel.

Lebanon considers itself at war with Israel, and although its military largely stayed out of the 2006 Israel-Hezbollah war, spying for Israel is considered an act of treason.

Prime Minister Fuad Saniora, a major Hezbollah foe in the election, has complained to the United Nations about the alleged spying networks, accusing Israel of violating Lebanese sovereignty and a U.N.-brokered truce that ended the 2006 fighting.

Lebanese security forces said they began the crackdown in April. The most recent incident came May 18, when officials said two Lebanese citizens fled to Israel, walking across the heavily fortified frontier.

Of those in custody, all are accused by Lebanon of providing intelligence to Israel on Hezbollah officials and positions, including one who sought information on the location of Nasrallah, who has been in hiding since the 2006 war.

The suspects also include a former security general, two members of the Lebanese security forces, the deputy mayor of a town in eastern Lebanon, a math teacher, a truck driver and a housewife. All face the death penalty if convicted.

Exactly how Lebanese authorities managed to break up the alleged espionage network remains unclear, but police have displayed sophisticated devices they say were seized from those arrested. They included a landscape survey sensor concealed in the cap of a water cooler, a car battery jump charger that transmits data and other electronic items hidden in furniture.

Lebanese police commander Brig. Ashraf Rifi attributes the arrests to "a technical secret" he would not disclose.

A senior Lebanese security official involved in the investigation, speaking on condition of anonymity because of the sensitivity of the information, attributed the arrests to "a very important technological advance."

Lebanese security officials say that since the 2006 war, Israel's focus has shifted to human intelligence after Hezbollah's successful concealment of its rocket and missile batteries from aerial reconnaissance. Rifi described the arrests as a strategic blow to Israel's intelligence-gathering efforts in Lebanon, and said they would take years to rebuild.

Yemen and Iran, plus Egypt — which has a peace treaty with Israel — have all charged some of their citizens with spying for Israel in recent years. In 1997, two Mossad agents were arrested in Jordan, which also has a peace treaty with Israel, after a botched attempt to kill Khaled Mashaal, leader of the Palestinian Hamas militant group, by spraying him with poison. The Israelis were later released.

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Associated Press writer Josef Federman contributed to this report from Jerusalem