He praised Egyptian officials for doing "an enormous job" of arresting many extremists after the last attacks, but said: "I don't think they cleaned out all of them, and new members have been drafted. And therefore Sinai remains a target."

In Washington, a U.S. counterterrorism official, who spoke on condition of anonymity in compliance with office policy, said it was unclear who was behind Monday's attack. Officials there have not ruled out al-Qaida involvement, but have no evidence showing that is the case, the official said. Nor do they have any evidence that bin Laden's tape was linked to the attack.

Dahab, which means "gold" in Arabic, was for years a popular, low-key haven for young Western and Israeli backpackers drawn by prime scuba diving and cheap hotels. In recent years, a number of more upscale hotels have been built, including a five-star Hilton resort.

Those who work in the town fear the attacks will drive tourists away ¡ª for good.

"The scene out there was horrific," said Mohammed Gadallah, a 27-year-old Egyptian from the Nile Delta region who works at a hotel coffee shop near the bridge bomb.

"I don't know who could have done this ¡ª they are people who know no religion and have no conscious. We have left our homes and families and come here to make a living. ... It looks like we'll be going back home."