A report published Thursday by The Washington Post, quoting current and former CIA veterans, revealed that the CIA informed Italy's intelligence service about its plan to kidnap an Islamic leader in Milan two years ago.
However, neither the Italian authorities nor Washington have officially acknowledged the abduction.
On Friday, the Corriere della Sera daily in Rome reported that a judge had issued arrest warrants for 13 CIA agents.
The Imam’s kidnapping fueled anti-U.S. feelings in Italy.
On February 17, 2003, Abu Omar, or Usama Mustafa Hassan, was snatched by two Italian-speakers who claimed they want to check his identity in a street of Milan.
The Imam has been missing since, the paper said.
Abu Omar was the former imam of a Milan mosque; placed under close watch, following the Sep 11 attacks in the United States.
The CIA is accused of kidnapping the Muslim Imam and transferring him to the U.S. military base at Aviano in Italy, and from there to Egypt, where he was put in jail.
Italian Judge Chiara Nobili issued the request of the anti-terrorist division of the state prosecutor's office.
Among the 13 wanted CIA agents is the alleged head of the operation, who was an accredited diplomat with the U.S. consulate in Milan in 2003, the Italian daily said.
A CIA veteran told The Washington Post on Thursday that the CIA "told a number of people" about its kidnapping plan, but "certainly not the magistrate, not the Milan police".
The CIA station chief in Rome, who retired at that time but remains undercover, sought approval from his counterpart in Italy for the operation, the agents said.
But it remains unclear how far up the chain of command the information was shared or whether the office of Prime Minister Silvio Berlusconi was aware, according to the Italian newspaper.
CIA officials say that the operation was conceived by the Rome CIA station chief and organized by the CIA's Counterterrorism Center, and approved by the CIA leadership and at least one person at the National Security Council.
The officials added that it was standard practice for the CIA and its Italian counterpart to agree to keep official silence on the covert kidnapping operation if it became public.
The Post said it was informed by Knowledgeable intelligence officials that the CIA has conducted at least 100 such operations since September 11.
The Italians are now demanding their government to say whether it did secretly authorize the kidnapping.
If it turned out that Italy’s government did not approve the operation, the center-left opposition says it would raise serious concerns about U.S. intervention.
The 13 agents are believed to have left Italy; none of them have been arrested.
According to some analysts, the Milan abduction threatens the relations between the two allies, already strained since March when U.S. troops killed an Italian intelligence agent in Iraq.
"Either the (Italian) government knew about the kidnapping ... or the government was not even informed by the American intelligence service over its activity in Italy," opposition Senator Antonello Falomi told Italian media.
"In either case, it's another terrible sign of this government's submission to U.S. interests."