The suspect, who has Palestinian roots, was apprehended for having links to international terrorism and is accused of “having joined the terrorist, Islamic pseudo-state, IS,” anti-mafia and terrorism chief Federico Cafiero de Raho told reporters.
Officials arrested the 28-year-old in Macomer on the island of Sardinia following a tip-off.
“He was planning an attack with ricin and anthrax,” Cafiero De Raho told reporters, naming the man as Alhaj Ahmad Amin.
Amin, 38, who is a legal immigrant and married with three children, was arrested in Macomer earlier in the day by hooded police who forced him from his car as he left home.
Amin had recently withdrawn all his money from the bank and was searching for his passport, Cafiero De Raho said: “He must have been close to doing something.”
After an IS member was arrested in Lebanon for plotting to poison the drinking water of the Lebanese army, it emerged he had a cousin in Italy who “had the idea to carry out a similar operation in Europe”, police said.
Numerous references to IS and the use of poison had been found on the man's smartphone.
The streets around the centre of Macomer were blocked off to prevent the suspect from getting away, according to local media reports. He was put in handcuffs as he came out of his house and got into his van.