'IS bio attack' foiled by German police

Germany's national police chief has said officers foiled a major biological attack with the arrest of a Tunisian man who possessed deadly poison ricin and bomb-making material.

German police commandos stormed a Cologne apartment last week and arrested a Tunisian man who was allegedly attempting to make a biological weapon and was said to have links to the Islamic State group.

Sief Allah H. started buying the equipment and ingredients to make ricin in mid-May and purchased "a thousand castor seeds and an electric coffee grinder", according to prosecutors.

"Very concrete preparations had been made for an act with a... biological bomb, which is a first for Germany," Holger Muench, head of the Federal Criminal Police Office, told public broadcaster ARD.

Produced by processing castor beans, ricin is 6,000 times more lethal than cyanide and has no known antidote.

The man was thought to be following instructions from the Islamic State group on how to build a bomb using ricin, German news weekly Der Spiegel reported.

He had managed to produce ricin earlier this month but it is still unclear whether he was actively plotting an attack.

Muench said "we became aware of this person a few months ago, and then evidence emerged pointing to links to the so-called Islamic State".

Bild daily said Germany received a tip-off from the CIA based on the suspect's online purchases.

Following the raid, police "found a large number of castor seeds from which to make it (ricin), as well as the utensils you need to make an explosive device", Muench said.

"Which concrete target he had in mind we don't know yet ... and the question of possible accomplices also remains open," he added.

French authorities said a month ago that they had foiled a terror attack possibly involving the use of ricin. Two brothers of Egyptian origin were arrested.

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 that claimed 12 lives.