The prime minister's remarks, building on a statement Tuesday by Foreign Minister Gianfranco Fini, showed that his government is determined to challenge the U.S. version of the Italian's death, which has strained relations between the two countries.

Though Berlusconi has come under growing domestic criticism for keeping 2,700 Italian troops in Iraq, his speech drew a standing ovation from opposition senators as well as members of his governing coalition.

In the weeks after Sgrena was taken hostage in Baghdad on Feb. 4, Italian intelligence officers worked to identify the kidnappers, determine that she was still alive, locate her and negotiate her release. Along the way, Fini said, information was shared with the U.S. Embassy's hostage working group in Baghdad.

Nicola Calipari, a senior intelligence officer familiar with working in Iraq, arrived with a colleague at Baghdad International Airport on Friday. Calipari spent 40 minutes contacting U.S. military authorities in charge of the airport to notify them of his mission and receive a safe-conduct document to move around the airport, according to the Italian leaders.

Neither Berlusconi nor Fini explained how contact was made with the kidnappers or who they were. But by their account, the two operatives left the airport and, after a two-hour wait in a Toyota Corolla near the Mansour district of Baghdad, were approached by a green van and led through various parts of the city.

At an unlit area, the van stopped, the driver pointed to an abandoned car and drove off. Sgrena was inside the car, dressed in black and blindfolded.

Calipari put the journalist in the back seat of the car and, with his colleague driving, they headed toward the airport, where a plane was waiting to take them back to Italy.

With the inside light on, Calipari sat alongside Sgrena and made phone calls to superiors to report his success. One was to an Italian official who was standing next to an American colonel at the airport, the prime minister said Wednesday, addressing the Italian Senate.

Calipari "therefore warned the American military officials of their immediate arrival in the airport zone," Berlusconi said.

"Only a frank and reciprocal recognition of final responsibility" will assuage Italians' anguish over the shooting, "which was so irrational to us," Berlusconi said.

U.S. Army Gen. George W. Casey, the top American commander in Iraq, said Tuesday in Washington that he had been unaware on Friday that Italian officials had entered Iraq to rescue Sgrena and said he had heard nothing since to indicate the Italians had told U.S. forces of the car's route.

In a statement after the shooting, the Army's 3rd Infantry Division said the Italians' car was "traveling at high speeds" and refused to halt at a checkpoint despite attempts by U.S. soldiers to warn the driver to stop "by hand and arm signals, flashing white lights, and firing warning shots in front of the car."

Fini, citing testimony by the driver, also an intelligence officer, said Tuesday that the car was traveling at no more than 25 mph as the driver steered around concrete blocks. Fini said the driver was applying the brakes when the car was hit by gunfire that lasted 10 to 15 seconds.

A Pentagon spokesman on Wednesday declined to comment on the Italian leaders' accounts on grounds that the matter is under investigation. "The information from the Italians will be considered as part of that investigation," he said.

When Sgrena was seized, a radical Web site operated by the Islamic Jihad Organization asserted responsibility and gave Italy 72 hours to withdraw its troops from Iraq. It did not say what would happen to Sgrena if Italy did not comply.

The Italians did not know who had seized the journalist. But channels were opened through a variety of sources, including religious organizations and friendly Arab governments, the Italian leaders said. They were seeking, among other things, assurances that the reporter was still alive.

On Feb. 16, she was shown in a video sobbing and pleading for her life. The Italians saw the video as a response to their feelers and a sign of progress in identifying her captors.

Berlusconi, like Fini, described the shooting as an accident. Italian newspapers have reported that a ransom of $6 million to $8 million was paid for Sgrena's release, but neither leader mentioned any payment.