FBI alerts apartment managers

WASHINGTON (CNN) -- Citing an "abundance of caution," the FBI is asking apartment managers to be on alert for suspicious activity, based on indications that al Qaeda leaders discussed the possibility of renting apartments in various parts of the country and rigging them with explosives, an FBI official told CNN.

The official, who could not say how the FBI came across this information, said it has no information the "proposed plot advanced beyond the discussion stage."

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The FBI has not issued a formal alert or advisory because the information is uncorroborated and is not specific to any city or region, the official said.

This past week, the FBI's counterterrorism headquarters notified the agency's 56 field offices to get in touch with their joint terrorism task force members at the state and local levels "to get the word out" to apartment managers and others overseeing rental properties, the FBI official said.

In some cases, the FBI is contacting rental properties directly, the official said.

The official said the move was done in an abundance of caution and said the FBI will continue to do this, even in cases where there is uncorroborated information.

"Whenever instances come up that we feel need to be passed along to the citizens, we are going to do this," the official said.

It is the first such precautionary alert to apartment building managers since the September 11 attacks, the official said.