Twenty-five Islamic extremists have illegally entered the U.S. since March as stowaways on cargo ships, federal officials told Fox News Monday.
The U.S. Coast Guard has notified federal, state and local officials that it has received intelligence information that the extremists have entered the U.S. on "prominent commercial cargo vessels," according to federal officials who read a Coast Guard document to Fox News.
The Coast Guard document says the "25 Islamic extremists" entered through the ports of Miami; Savannah, Ga.; and Long Beach, Calif.
The document, dated May 10, was read to Fox News by government officials in two separate federal agencies. It indicates that a classified briefing will take place on Tuesday to provide specifics to various law enforcement officials about the nature of the Islamic extremists and the quantity and quality of the information that the government has obtained.
A Bush administration official told Fox News that the document is based on intelligence information whose "credibility has not yet been determined."
Government officials point out that there has been no change in the nationwide alert level, and not all agencies and law enforcement communities have been contacted about this.
The development comes as U.S. intelligence officials confirmed a report in the Washington Times that they have received threats that terrorists will strike a U.S. nuclear power plant July 4, and are reviewing the information to determine whether it is reliable.
The government is taking the July 4 threat seriously, though officials have preliminarily determined that the information is not credible enough to act upon, said a government official familiar with the investigation.
The threat initially was believed to have come from Al Qaeda leader Abu Zubaydah, who was captured by U.S. forces and is undergoing interrogation. But officials told Fox News on Monday that the threat came from an 'unverified, untested' Eastern European intelligence service.
An official said the alleged Independence Day plot is one of scores of threats filtering through U.S. intelligence and is not considered serious enough to formally warn the American public or change the nuclear industry's already high level of alert.
"We hear about potential threats tied to specific dates all the time — Christmas, New Year's, Ramadan..." the official said.
He said federal authorities take the threats seriously and take precautions, but he said that doesn't make the threats any more credible.
The threat received last week suggested that an unidentified Islamic terrorist group is planning to attack the Three Mile Island nuclear facility in Pennsylvania or another plan elsewhere in the Northeast, the source said.
Fox News' Carl Cameron and Catherine Herridge and The Associated Press contributed to this report.