The Obama administration is expected to issue an alert to U.S. citizens in Europe, urging them to be vigilant after new intelligence pointed to new Al Qaeda threats, senior U.S. intelligence officials told Fox News.
The State Department is expected to announce the travel alert Sunday morning, the officials said.
The officials said the State Department was never considering issuing a travel warning, which advises Americans to stay away from the countries involved.
Still, the move could have negative implications for European tourism if travelers fear there's a possibility of terror attacks.
A European official briefed on the talks told the Associated Press that the language in the U.S. alert is expected to be vague; it won't address a specific country or specific landmarks.
European and U.S. officials have not identified any specific targets that terrorists might be considering, the official said. Officials have called the threat credible but not specific.
The U.S. has told European leaders that the State Department alert would be intended to raise the warning level to match the information about the would-be attack that surfaced last week, the European official said.
The European official said there had not been strong opposition to the proposed alert from European leaders.
Intelligence officials believe Usama Bin Laden is behind the terror plots to attack several European cities. If this is true, this would be the most involved role that bin Laden has played in plotting attacks since Sept. 11, 2001.
The latest intelligence shows that Bin Laden was directly involved in trying to execute what an intelligence official emphasized was a multiple-city Mumbai-style attack.
"It's clear and the plot is clear. The clarity of detail on the plans for these attacks is disturbing," the official told Fox News.
There was "some degree of coordination between the multiple teams of attackers targeting at least three Western European cities, but not all know when to hit," the official said, adding the goal was to kill many, many more than the 173 killed in Mumbai.
Eight Germans and two British brothers are at the heart of the terror plot against European cities, but the plan is still in its early stages, with the suspects calling acquaintances in Europe to plan logistics, a Pakistani intelligence official said Thursday.
One of the Britons died in a recent CIA missile strike, he said. The Pakistani official said the suspects are hiding in North Waziristan, a Pakistani tribal region where militancy is rife and where the U.S. has focused many of its drone-fired missile strikes.
"We remain focused on Al Qaeda's interest in attacking us and attacking our allies," Crowley said. "We will do everything possible to thwart them and will take steps as appropriate."
The implications of a blanket "travel warning" for all of Europe could be big. There are hundreds of thousands of Americans in Europe at any one time, including tourists, students and businesspeople.
While the government cannot stop people from traveling there or force them to return home, a warning could result in canceled airline and hotel bookings as well as deter non-U.S. travelers from going to Europe. In addition, many U.S. college and university study-abroad programs will not send students to countries for which a warning is in place for insurance and liability reasons.
For that reason, officials said, there was internal debate over how strong to make the warning. The State Department has several grades of travel notice, ranging from low-threat advisories to more severe alerts and a formal "travel warning." There is also a "worldwide caution" in place that warns Americans of ongoing global terrorist threats.
Some U.S. allies in Europe have expressed concern about the proposed warning, saying it is an overreaction to the threat information, a position shared by some in the administration, the officials said.
The French Foreign Ministry, Interior Ministry, the national police and the Paris police all declined immediate comment. Calls to the Paris tourism office and the French government's tourist office in the United States went unanswered Saturday and there was no immediate response to e-mail requests for comment.
A spokeswoman for the German Foreign Office in Berlin declined comment
Under a "no double standard" rule adopted after the 1998 bombings of the U.S. embassies in Kenya and Tanzania, the government is obliged to share threat information that it has given diplomats and other officials with the general public.
Fox News' Jennifer Griffin, Justin Fishel and The Associated Press contributed to this report.