CAIRO, Egypt — Western governments are heightening their alerts for possible reprisal attacks from Hezbollah on Jewish and Israeli targets.

The FBI last week sent out a memo to its regional offices as a general warning that such strikes could be coming.

While both the FBI and Jewish organization officials familiar with the warning stress that no specific threats against American Jewish targets have been detected, Jewish organizations passed on the information to member groups last week through the recently created “secure community network,” which was established to share threat data for Jewish organizations.

An FBI spokesman said yesterday that there was no information of an “imminent attack” from Hezbollah, but that the bureau had increased its focus on the group now fighting Israeli special forces in southern Lebanon.

Already, according to the Globe and Mail newspaper, British counterterrorism officials have said they are raising the alert for attacks on Jewish and Israeli targets in Britain. On Monday, the German newspaper Bild quoted the German interior minister, Wolfgang Schaeuble, as saying, “The longer the conflict continues, the greater becomes the danger of terror actions in other countries.”

“This was a general advisory,” the executive vice chairman of the Conference of Presidents of Major American Jewish Organizations, Malcolm Hoenlein, said yesterday, referring to the FBI memo. “We have not heard anything that would indicate a specific threat. This is more of a general concern,” he said.

“At this time, there is no specific or credible intelligence pointing to an imminent attack by Hezbollah in the United States,” an FBI spokesman, Paul Bresson, said. “The FBI has increased its focus on Hezbollah. Those investigations focus specifically on Hezbollah’s recruitment, training, and fund-raising activities on U.S. soil and abroad.”

Analysts and government sources familiar with the threat assessment from Hezbollah say they fear the use of terrorism as a possible counter-attack if the group’s main militia in southern Lebanon feels it would soon be defeated on the battlefield. It would not be the first time that Hezbollah used a terrorist attack abroad in response to a military setback on its home turf. On July 18, 1994, the organization’s operatives bombed the Amia Cultural Center, a center of the Jewish community in Buenos Aires, in response to Israel’s bombing on June 2, 1994, of the Ein Dardarah training camp.

A former chief of the FBI counterterrorism division in charge of Iran and Hezbollah, Kenneth Piernick yesterday said, “If I was an owner of a security services firm for an Israeli friendship society, or in charge of security at an Israeli embassy or Israeli business I would be very tense right now. Frankly, any high visibility internationally known Jewish business is potentially a target.”

Mr. Piernick said he thought that if Iran’s revolutionary guard and Hezbollah’s military leadership chose to do so, it would be more likely that they would identify a target in South America, Central America or Africa, where security measures are less tight. “Hezbollah, they are pros at what they do. At the time and venues of their choosing they can strike,” he said. “Without having any knowledge, I would bet they are improving their target sets. They have done surveillance on these targets. They are always preparing. They are probably refurbishing their surveillance data to make sure they are viable today.”

Mr. Piernick added, “They have a series of operations already in the can. That is 90% of the work. The selections and surveillance have been done. They probably have a series of targets across the globe, including the United States, though this is less likely than other places. Despite our open borders, the United States has a much better security atmosphere than in South America or Africa.”

A terrorism expert who has worked closely with the FBI against Islamist organizations in America, Steve Emerson, yesterday said, “There is a concern that Hezbollah could attack Jewish targets, they know this does not play well for attacking Americans.” Mr. Emerson added that Hezbollah’s leader, Sheik Hassan Nasrallah, “has talked about hitting Zionists anywhere in the world. If their back is against the wall, they might strike out.”

In an interview from Israel yesterday, the national director of the Anti-Defamation League, Abraham Foxman, said, “It is not a secret we are dealing with true believers who have been recruited or placed around the world. Certainly one is not naïve enough to think they would not be in the United States. Every time that the situation heats up in the ground or in the air in the Middle East, the alerts and antenna go up.”