Prosecutors are probing a letter in Arabic threatening to behead justice minister Andrea Orlando mailed to his office in Rome on Thursday with two bullets and signed by the Islamic State jihadist group.
"We will enter Rome and cut off your head. Allah is great," reads the letter.
Orlando received message of solidarity from lawmakers of all political stripes and from the country's top office-bearers condemning the letter.
"These threats won't stop us and whoever seeks to spread fear will fail. We will react by continuing to dialogue, not hiding by away," Orlandi wrote on his Facebook page.
"Our duty is to defeat terrorism by defending the principles of freedom and equality which underpin civil society," Orlandi added.