MILAN, Italy -- The men spoke in code of a mysterious "drug" they wanted to try on people. One referred repeatedly to the substance as "tomato cans" and said he wanted to see what effect it would have on someone breathing it in.
The conversation between suspected members of Osama bin Laden's terrorist network was cryptic, but authorities in Italy think they know what the men were talking about: obtaining cyanide, a poison used to make deadly chemical weapons.
A tape of the conversation, recorded in March, is part of evidence gathered in an investigation into an apparent plan for chemical attacks by groups linked to bin Laden, raising fears that they intended to use unconventional weapons to inflict casualties on a large scale.
Suspicion emerged last December when German authorities arrested four suspected terrorists in a raid on two apartments in Frankfurt, Italian prosecutor Stefano Dambruoso told The Associated Press last week.
German authorities seized conventional arms and explosives in the raid and found a manual on how to make chemical weapons, Dambruoso said.
The four suspects in Germany were accused of plotting to bomb an outdoor market in Strasbourg, France, at the end of 2000. Several of them had been in contact with Essid Sami Ben Khemais, later identified by Italian authorities as a top al-Qaida operative in Europe who headed a terrorist cell in Milan, Italy.
Italian investigators said there is also evidence that the Milan cell was linked to chemical weapons.
An Italian investigative report, part of which Dambruoso allowed the AP to review, contains excerpts from wiretapped conversations among members of the Milan cell, including Ben Khemais. Italian, Spanish and French prosecutors have identified Ben Khemais as a top al-Qaida operative who helped supervise operations throughout Europe.
In one phone call, excerpts of which were among the material reviewed by AP, Ben Khemais spoke of an unspecified "drug," also referring to it as "tomato cans," according to the report.
"I'd like to learn how to use the drug and see the effect on someone breathing it," he said in the taped conversation.
Italian authorities say they believe the phrase "tomato cans" -- which was repeated many times throughout several conversations -- was code for cyanide, an easily obtainable poison that can be used as a chemical weapon. Dambruoso would not say what specific evidence authorities have that the weapon being discussed was cyanide.
"Do we have hard evidence they possess chemical weapons? No. Is it very possible they have them? Yes," Dambruoso said.
The conversations were recorded in March, a month before Italian police arrested Ben Khemais and four other suspected members of the group, all Tunisian. The five are expected to be brought to trial in December.
Bin Laden has hinted that his group has chemical, biological and even nuclear weapons. U.S. officials have said al-Qaida probably has crude chemical or biological weapons but not a nuclear bomb.
"This is a real threat, and it has to be treated as such," said Walter Purdy, a board member of the Terrorism Research Center in Washington.