Washington (CNN) -- The al Qaeda group that built two toner-cartridge bombs in an unsuccessful attempt to blow up planes in October also has contemplated spreading poison on salad bars and buffets at U.S. hotels and restaurants, U.S. officials told CNN Tuesday.
But U.S. officials sought to downplay the threat -- first reported by CBS News -- saying it was months old, and that it was more in the nature of a discussion of "tactics" than an actual plot. Officials implied the tactic is beyond the capabilities of the terrorist organization, which is based in the Middle East.
The United States has received information the group -- al Qaeda in the Arabian Peninsula -- was considering the tactic of placing ricin and cyanide poisons into food supplies, Department of Homeland Security officials confirmed to CNN.
In response to that information, U.S. officials met through regular channels with representatives of the hotel and restaurant businesses to discuss the possibility that terrorists could target the food supply, and to reiterate "best practices" to ensure the food supply is safe.
Officials, however, likened the threat to numerous others discussed in jihadist publications such as the online magazine Inspire, where al Qaeda members and sympathizers discuss various ways to attack Western countries.
"We're talking months, not weeks (ago), that this came into the threat stream," one official said.
Earlier this year, the federal government staged a tabletop exercise, or role-playing drill, in which the government and industry practiced responses to a fictional incident involving "intentional contamination" of food. A Homeland Security Department official said the drill was not a direct response to the threat information, but that the threat from al Qaeda in the Arabian Peninsula, known as AQAP, helped define the scenario and add to its authenticity.
The group that held the exercise -- the Food and Agriculture Sector Coordinating Council -- declined to discuss the threat, referring CNN's calls to the Department of Homeland Security.
The CBS report quoted an unnamed intelligence source saying the threat was "credible."
But officials told CNN they did not believe the threat was in any advanced stage of planning.
"We're aware that terrorists have been interested in doing this kind of thing for a long time," one U.S. official told CNN Pentagon Correspondent Barbara Starr. "They've said as much and, as a result, we take all of this very seriously. But we don't know of any current plotting along these lines."
Homeland Security Department's only official comment came in response to the CBS report.
"We are not going to comment on reports of specific terrorist planning. However, the counterterrorism and homeland security communities have engaged in extensive efforts for many years to guard against all types of terrorist attacks, including unconventional attacks using chemical, biological, radiological, and nuclear materials," spokesman Sean Smith said in a prepared statement.
"Indeed, (al Qaeda) has publicly stated its intention to try to carry out unconventional attacks for well over a decade, and AQAP propaganda in the past year has made similar reference. Finally, we get reports about the different kinds of attacks terrorists would like to carry out that frequently are beyond their assessed capability," the statement said.
Some terror experts said food poisoning may be within al Qaeda's capabilities.
It's "easier to do this than get a bomb on a plane or make a sophisticated biological weapon that you would spray in the air," said Randall Larsen, a homeland security expert. "This is very crude, it's very simple, and with knowledge you get in a high school biology class, you could produce something that would cause a problem."
"It's good that the word is out there, because people in public health departments really need to know about this, so if they start seeing something coming into emergency rooms, they're kind of ready to look for it and to watch for it," Larsen said. "And ... restaurant owners and people like that (need) to know about this if there's a potential threat."
While ricin and cyanide can sicken or even kill people, neither is considered a weapon of mass destruction, Larsen said.
Experts say terrorists have long considered the possibility of contaminating water and food supplies with chemical or biological substances, and that both ricin and cyanide have been in the terrorists playbook. Ricin, a natural, highly toxic compound, is extracted from castor beans.
In 1978, Bulgarian dissident Georgi Markov was shot with a ricin-tipped dart fired from an umbrella while waiting for a bus in London. He died four days later. And in 2004, ricin was found in a letter in Sen. Bill Frist's mailroom in a letter demanding changes in truckers' sleep/work schedule rules.
The idea of contaminating salad bars also is not original. In 1984 members of an Oregon cult contaminated salad bars with salmonella, sickening hundreds of people in an attempt to influence a local election that day.
But if AQAP is contemplating such an attack, it would be a shift in direction.
CNN National Security Contributor Frances Fragos Townsend said AQAP "seems very focused on (creating) an improvised explosive device, preferably involving aviation."
AQAP, was behind the October attack on two cargo planes. The group created bombs out of printer toner cartridges, but the devices were discovered and disarmed before they detonated. AQAP also has claimed credit for the September 6 crash of a UPS cargo plane in Dubai, but U.S. authorities say there is no evidence they played a role in the crash.