Germany has arrested two Iranian brothers on charges of planning an attack using lethal toxins, prosecutors say.
The two men, aged 32 and 25, allegedly sought to use cyanide and ricin "in order to kill an indefinite number of people," the prosecutor's office said in a statement on January 8.
The brothers, whose names were not released, were motivated by Islamic extremism, prosecutors said. They did not appear to be acting on behalf of the Iranian state, an unnamed German security official told dpa.
Police wearing protective suits against a potential chemical hazard detained the men during an early morning raid of their home in Castrop-Rauxel in western Germany.
Investigators did not uncover any traces of the toxic substances during an initial search of the premises, German prosecutors said.
It wasn't immediately clear how far advanced the plans for an attack were and whether the suspects had picked a specific target.
Initial reports said the older brother, who allegedly supports a Sunni extremist group, was the architect of the plan and had received some help from his younger brother. Sunnis are a religious minority in Iran.
The two men will be charged with "conspiracy" to commit murder, a crime which could carry a prison sentence of between "three to 15 years," prosecutors said.
"Our security forces take every suggestion of Islamist terror threats very seriously and act accordingly," federal Interior Minister Nancy Faeser said in a statement.
Germany has been targeted in recent years by several Islamist attacks, including a 2016 truck attack on a Christmas market that killed 12 people and left dozens injured.
German officials said they had been tipped off to the plot by the U.S. Federal Bureau of Investigation (FBI).
The FBI allegedly infiltrated a Telegram chat group where the two suspects "asked about bomb construction plans and later about toxins,"according to a report by Spiegel weekly.
In 2018, a Tunisian man and his wife were arrested on suspicion of planning a chemical attack in Germany.
The two, who sympathized with the Islamic State group, were found in possession of 84 milligrams of ricin in their Cologne apartment.
They were both handed long prison terms.