German police said Wednesday they had foiled a biological attack with last week's arrest of a Tunisian suspected jihadist in possession of the deadly poison ricin and bomb-making material.
"Very concrete preparations had been made for an act with a ... biological bomb, which is a first for Germany," said Holger Muench, head of the BKA Federal Criminal Police Office.
German police commandos on June 12 stormed the Cologne apartment of the 29-year-old Tunisian identified only as Sief Allah H. and discovered "toxic substances" that turned out to be ricin.
Produced by processing castor beans, ricin is lethal in minute doses if swallowed, inhaled or injected and 6,000 times more potent than cyanide, with no known antidote.
Muench said, speaking to German public radio, that "we became aware of this person a few months ago, and then evidence emerged pointing to links to the so-called Islamic State".
The Tunisian man, who has been charged with violating German law on the possession of weapons of war and "preparing a serious act of violence against the state", was thought to have followed instructions on making a ricin bomb disseminated online by the IS.
"There are instructions on how to do this, including by Islamist organisations, on the Internet, and this person was obviously guided by that," Muench said.
Prosecutors last week charged that he was "strongly suspected of intentionally manufacturing biological weapons" -- but they had so far said it remained unclear whether the suspect was actively plotting an attack.
The head of the BND foreign intelligence service, Hans-Georg Maassen, said that a "very likely" attack had been prevented thanks to "cooperation between security service at the national and international level," news agency DPA reported.
Bild daily has reported Germany received a tip-off from the CIA based on the suspect's online purchases.
The domestic intelligence service BfV said it also received a tip-off over a telephone hotline about the Tunisian, who is married to a German woman who recently converted to Islam, DPA reported.
During the police raid, said Muench, "we found a large number of castor seeds from which to make (ricin), as well as the utensils you need to make an explosive device".
"Which concrete target he had in mind we don't know yet ... and the question of possible accomplices also remains open."
Prosecutors say Sief Allah H. started buying the equipment and ingredients to make ricin in mid-May -- including an online purchase of "a thousand castor seeds and an electric coffee grinder".
He succeeded in manufacturing the toxin earlier this month.
The case comes after French authorities in mid-May said they had foiled an attack possibly involving ricin with the arrest of a 20-year-old Egyptian man.
Interior Minister Gerard Collomb said the attack would have been committed "with explosives or ricin, this very powerful poison", and that the suspect "had tutorials that showed how to make ricin-based poisons".
The Egyptian man was tracked down through a pro-jihadist social media account, a source close to the investigation said.
Germany remains on high alert after several deadly attacks claimed by the IS group, including a 2016 truck rampage through a Berlin Christmas market by Tunisian asylum seeker Anis Amri that claimed 12 lives.
Other attacks by radicalised Islamists saw a 26-year-old Palestinian stab six people, killing one, in Hamburg last year, and a 17-year-old Afghan with an axe attack five train passengers in Munich before police shot him dead in 2016.
Muench said security services are now more worried about the threat of radicalised individuals, including 770 persons considered by police as potentially violent, than an organised large-scale attack.
After the defeat of major IS bastions in Syria, he said, "we now consider a major attack like we saw in Paris and Brussels not entirely unlikely, but less likely because the so-called Islamic State has been weakened quite substantially."
"But we have a large number of radicalised persons and we need to keep an eye on them".