Israeli intelligence experts increasingly think Hezbollah is determined to attack an Israeli target - most likely institutions or officials abroad, especially in third-world countries - to avenge the assassination of one of Hezbollah's top leaders.

Another, less likely, possibility is that Hezbollah will attempt to kidnap Israeli businessmen abroad.

Israeli military and security officials told Haaretz on Tuesday night it appears that Hezbollah wants to attack Israeli targets even though several previous attempts have failed.

Over the last few weeks, Hezbollah leaders have been taking a particularly aggressive line in public threats against Israel, saying such attacks would be in revenge for Imad Mughniyeh's assassination and to "liberate the Shaba Farms," an area along the northern border that Israel refers to as Har Dov. The Lebanese Shi'ite group blames the Mossad for the February explosion that killed Mughniyeh in Damascus.

U.S. television stations, basing their information on American intelligence sources, reported in mid-June that a Hezbollah cell had been caught collecting information on Israeli targets in Canada, including the Israeli Embassy in Ottowa.

Israeli security officials at embassies and consulates abroad have been on high alert since Mughniyeh's death.

Defense Minister Ehud Barak called on Israelis to heed terror threats when heading out of the country.

"There have been quite a few alerts in the last few weeks, and there were several very important deflections [of planned attacks]," Barak said during a visit to an Israel Defense Forces base in the Negev. "I can only tell Israeli citizens once more: Being Israeli is a responsibility, and we must take seriously the counterterrorism unit's warnings, especially ahead of the holidays regarding trips to Sinai, but also other places. Use your common sense."

Barak did not provide further details about the thwarted Hezbollah attacks, and a defense source told Haaretz that the time was not yet ripe to elaborate.

"The time has not yet come to release all of Hezbollah's plans that have been foiled recently," the defense source said. "It's not just that we've warned a few businessmen not to be tempted by offers that were liable to end in abductions. A lot of preventative activities are being undertaken, at various levels, and their result so far is that there have not been any terror attacks but the danger has not passed."