JERUSALEM —  Israeli security instructed embassies and Jewish institutions around the world to go on alert Thursday for fear of revenge attacks for a car bomb that killed a top-wanted terrorist, Imad Mughniyeh, officials said.

Soon after the explosion in the Syrian capital of Damascus Tuesday that killed the Hezbollah fugitive, Israel insisted it was not the perpetrator. But the perception that Israel wanted Mughniyeh dead left the Iranian-backed militia and many in the Arab world pointing a finger at the Jewish state.

Mughniyeh was the suspected mastermind of several attacks that killed hundreds of Americans in Lebanon and of cruel kidnappings of Westerners.

Israeli embassies have gone on alert and Israeli security has instructed Jewish institutions to also be aware, Israeli officials said on condition of anonymity since they were not authorized to discuss security matters with the press. Israel's Foreign Ministry would not comment.

The Shin Bet security service has ordered security increased at several points, defense officials said on condition of anonymity due to the sensitive nature of the matter. Israel Radio reported that security had been raised on airplanes, and boats and at sensitive installations.

The army raised its awareness on its border with Lebanon and in the Palestinian territories for fear of attacks and kidnappings, the defense officials said. The Israeli army spokesman would not comment.

Mughniyeh's killing is expected to raise Israel-Hezbollah tensions and could ignite a new round of cross-border hostilities despite Israel's denial of involvement.