Updated

Israel has foiled an Al Qaeda plan to carry out a suicide bombing at the U.S. Embassy in Tel Aviv, Fox News confirmed.

According to a senior U.S. official who has been briefed on the intelligence shared by Shin Bet, Israel’s internal security agency, about the plot,  “we have no reason to question the Israeli intelligence.”

"Details are still emerging,” said the official, who described the plot as “audacious” and involving a “small cell.”

It is not clear that the plotters could have carried out all that they aspired to.

The State Department said the U.S. was not yet able to corroborate the Israeli claims.

Shin Bet said Wednesday it arrested three Palestinians it accuses of plotting to carry out bombings, shootings, kidnappings and other attacks. The Times of Israel reported that the arrests were made three weeks ago, shortly before at least one of the men was due to travel to Syria to make final plans for the operation. One of the suspected plotters, identified as Arib al-Sham -- a Gaza-based Al Qaeda point man for the attacks -- is still at large.

Shin Bet said the men, two from Jerusalem and one from the West Bank, were recruited by an operative based in the Gaza Strip who worked for Al Qaeda leader Ayman al-Zawahiri.

Shin Bet alleges the Palestinians planned on attacking a Jerusalem conference center with firearms and then killing rescue workers with a truck bomb.

It said Al Qaeda also planned to send foreign militants to attack the U.S. Embassy in Tel Aviv on the same day using explosives supplied by the Palestinians. According to the Times of Israel, other planned targets included an Israeli bus and Jewish homes in East Jerusalem. Shin Bet said that the Al Qaeda operatives planned to gain entry into Israel using Russian paperwork.

The security organization also said Wednesday that the foiled plot indicates that the civil war in Syria has not only drawn terror operatives throughout the region, but has enabled Al Qaeda and similar organizations to put down roots and attempt to link up with Palestinians in the West Bank and Jerusalem who would be willing to strike Israeli and Western targets.

Palestinian security officials are dismissing Israel's claim that it broke up a plot.

Adnan Damiri, a spokesman for the Palestinian security services in the West Bank, says there is "no indication" that Al Qaeda has a presence in the territory. He accused Israel of arresting some "boys" and exaggerating the nature of the threat to bolster its position in peace talks. Israel says it must retain a presence in parts of the West Bank after any peace deal because of security concerns.

Aviv Oreg, a former head of the Israeli military intelligence unit that tracks Al Qaeda, said the plot marked the first time it has been directly linked to an attempted attack in Israel.

"This is the first time that Ayman al-Zawahri was directly involved," he said. "For them, it would have been a great achievement."

In Washington, State Department spokeswoman Marie Harf said U.S. investigators and intelligence officials were not yet able to corroborate the Israeli information and declined comment on specifics of the case.

"Obviously we're looking into it as well," Harf told reporters Wednesday. "I don't have reason to believe it's not true. I just don't have independent verification."

She said there were no plans to evacuate the U.S. Embassy in Tel Aviv and was not immediately aware of stepped-up security measures there in light of the arrests.

Fox News' Leland Vittert and Jennifer Griffin and The Associated Press contributed to this report. 

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