Brazil's decision to free Italian ex-militant Cesare Battisti from prison will seriously affect the relations between the two countries, Italian President Giorgio Napolitano said on Thursday.
Brazil's Supreme Court denied Italy's extradition request and ordered Battisti's release.
The decision "causes serious damage to the agreements signed between Italy and Brazil" as well as to the fight against terrorism waged by Rome, Napolitano said.
Italian Prime Minister Silvio Berlusconi expressed "great regret" over the release of Battisti who had been sentenced to life for the murders of four people in the 1970s.
Foreign Minister Franco Frattini said Italy planned to use every judicial mechanism, including the International Court of Justice in The Hague, to overturn the decision.
Battisti, a member of the far-left Armed Proletarians for Communism group, escaped from an Italian jail in 1981 and spent decades living in Mexico, France and Brazil.
ROME, June 9 (RIA Novosti)