At least 12 Carabinieri, including one officer, were killed Wednesday as a blast hit the Italian police headquarters in the southern Iraqi town of Nasiriyah, the Italian news agency ANSA reported.
Italian Carabinieri Chief of Staff General Guido Bellini had just said that six were killed in the attack when he came to brief President Carlo Azeglio Ciampi on the situation.
These were Italy's first casualties since its troops joined the US-led stabilization force in Iraq.
Ciampi has called on all Italians to rally around the country's Carabinieri Corps.
In a televised statement to the country, Ciampi said his first thoughts went out to the relatives of those "killed in an ignoble act of terrorism. I share their sorrow and offer my full sympathy to the Carabinieri Corps."
Italian Foreign Minister Franco Frattini is also being kept fully informed on developments, government officials said.
A Portuguese eyewitness saw a truck explode outside the Italian Carabinieri barracks in Iraq, Bellini said.