The FBI is warning that terrorists could potentially use pens filled with cartridges of poison as weapons, according to an FBI bulletin obtained by Fox News.
A pen gun (search) is a small-caliber, single shot weapon that resembles a fountain pen.
In its weekly bulletin to law enforcement agencies throughout the country, the FBI said that bullet cavities of pen guns could be filled with poisonous chemicals or biological toxins, including cyanide (search), mercury (search), arsenic (search) and ricin (search).
"The FBI possesses no information indicating that chemical pen guns are currently being used or will be used in terrorist operations in the United States; however, law enforcement agencies should remain alert to the potential use of such devices," the FBI said in the notice.
The FBI noted, by way of background, that Indian authorities in December 2003 seized a pen gun during a raid on a suspected Islamic separatist's home in Kashmir, India. Police also found 25 suspected chemical cartridges (search). An officer became lightheaded after breaking open a cartridge. However, the chemical agent, if any, has not been identified.
"Pen guns are not new weapons; however, if the cartridges found in the Indian seizure were contaminated, that would indicate a new method of operation," the FBI said.
Since early 2001, several incidents involving pen guns have been reported overseas, according to the FBI. To describe a few:
— On June 18, 2003, Saudi Arabian border guards seized 10 pen guns from Yemini nationals.
— In January 2003, French police searching locations used by an arrested French Algerian baggage handler found a number of pen guns.
The bureau points out that pen guns can be easily concealed to evade detection at security checkpoints.
"Except for its heavier weight, which is evident only when held, a pen gun closely resembles a standard fountain pen. There are no outward markings to indicate the pen is a firearm," the FBI said.
"Furthermore, one type of pen gun has a tiny ink reservoir within the tip, so it will write if the operative is challenged. In a standard X-ray device, an unloaded pen gun may appear as a normal pen."
The FBI said a watch placed on top of a pen gun could obstruct the weapon when going through an X-ray. "Therefore, pens should be separated from other items in screening bins to ensure a clear X-ray image," the agency stated.
Pen guns are readily available in the United States and have recently become available in Europe, the Balkans, Middle East and South Asia, the FBI said.
Fox News' Anna Stolley contributed to this report.