A 32-year-old man has been taken into police custody in the western German state of North Rhine-Westphalia for allegedly preparing an "Islamist-motivated attack," police and prosecutors said in a joint statement on Sunday.

The man, identified as an Iranian, was "suspected of having prepared a serious act of violence that endangers the state by procuring cyanide and ricin to commit an Islamist-motivated attack."

Ricin is a highly toxic biochemical weapon.

Residence searched for 'toxic substances'

According to a press release issued by Munster police, Recklinghausen police and the Dusseldorf prosecutor's office, a residence in the town of Castrop-Rauxel in the Ruhr region was searched for "toxic substances."

An area around the suspect's residence was cordoned off as police and rescue workers were deployed to the site. The Deutsche Presse-Agentur (dpa) news agency reported that numerous emergency workers wore protective suits as they were deployed at the site.

Investigators said, "The search serves to find corresponding toxins and other evidence."

Investigators said that another person was arrested during the operation and taken into custody.

It has not yet been decided whether the 32-year-old will be brought before a magistrate.

What is ricin?

Ricin is a highly potent plant-derived toxin that works by entering the cells of a person’s body and preventing them from making the proteins they need.

It is listed as a biological weapon by both the United Nations and Germany's Robert Koch Institute for disease control and prevention.

The definition of biological and chemical weapons can overlap to an extent because biological weapons can include infectious bacterial or viral agents, or toxins derived from biological material.

The use of such toxins produced by some living organisms is covered under the provisions of both the international Biological Weapons Convention and the Chemical Weapons Convention.

sdi/kb (dpa, AFP)

Editor's note: This article was updated to reflect that ricin is listed as a biological weapon by both the United Nations and Germany's Robert Koch Institute for disease control and prevention.