ROME -- Italian investigators said Monday that nervousness and inexperience among U.S. troops contributed to the March 4 killing of an Italian intelligence agent at a roadblock as he tried to take a freed kidnap victim to the Baghdad airport.

In a 67-page report, the Italians countered conclusions released by American military authorities on Saturday that the agent's car was speeding and failed to respond to signals to stop. The soldiers acted properly, the U.S. report concluded, and will not face disciplinary measures.

"The Italian representatives, on the base of evidence that it has been possible to acquire, have not identified elements to suppose that the tragedy was willful," the Italian report said. "It is likely that tension, inexperience and stress led some of the U.S. troops to react instinctively and with little control."

Officials of the government of Prime Minister Silvio Berlusconi said the killing of agent Nicola Calipari would not affect Italy's close relations with the Bush administration. But the report, which followed a joint investigation of the incident, was peppered with criticisms of American action in Iraq generally and the U.S. response to the shooting in particular.

The report was released here the day after the full classified version of the American report, released in censored form on Saturday, showed up on the Internet. U.S. officials said that it contained information about tactics and casualties that could endanger U.S. troops.

The information was disclosed because of a technical error by U.S. military authorities, who posted the censored version on a military Web site in a form that allowed outside computer specialists to manipulate it and reveal the deleted portions.

"If you're a soldier on the other end of the rifle in Iraq, seeking to keep the enemy from knowing our vulnerabilities, it's very significant," said a Defense official, speaking on condition of anonymity because the matter is classified.

The March 4 shooting occurred in darkness, as Calipari was escorting Italian journalist Giuliana Sgrena to the airport after her release by kidnappers. Based on Sgrena's account that Calipari threw his body over her to protect her from the fusillade, he became a national hero. She was wounded.

His death brought to the surface simmering public opposition to the presence of 3,000 Italian troops in Iraq as part of the U.S.-led force. It also prompted an unusual break in the lockstep alliance between Berlusconi and President Bush. After the shooting, Berlusconi said he hoped to begin withdrawing Italian forces in September. He is scheduled to address both houses of Parliament on Thursday.

The Italian report countered U.S. findings that the incident grew in part from the failure of Italian officials to coordinate with American forces that the car would be coming through. It said U.S. authorities had a basic understanding of Calipari's mission, but it acknowledged they were unaware of his movements and details of his activity.

In any case, the report said it was neither necessary nor practical to notify U.S. military officials of movement on the well-traveled highway.

The U.S. troops failed to put up warning signs at a position that was meant to keep traffic from entering the road from an on-ramp, the report said. A duty log of the unit involved disappeared shortly after the incident, the Italians added.

The Italian report dismissed U.S. claims that the car was speeding as it approached the checkpoint, saying that the conclusion was based on soldiers' testimony, not an investigation of the scene.

Not only did the two armored vehicles stationed there depart to take Sgrena to a hospital, but U.S. forces quickly removed Calipari's bullet-scarred Toyota Corolla.

"That made it impossible to technically reconstruct the event, to determine the exact position of the vehicles and measure the distances, and to obtain precise data defining the precise trajectory of the bullets, the speed of the car and the stopping distance," the report concluded.

The Italians said U.S. investigators failed to carry out a count of the bullets fired and prohibited an Italian general, Mario Marioli, from visiting the site of the shooting.

In a terse critique of U.S. handling of roadblocks, the Italians wrote that the Americans generally resist supplying data and statistics "concerning 'fratricidal' incidents" and civilian casualties at checkpoints. The statement echoes complaints by human rights monitors who say the United States refuses to divulge or take blame for deaths of innocent civilians on Iraqi roads.

The U.S. military in Iraq is conducting an inquiry into the mistaken release of the full classified report and is assessing the magnitude of the security breach, the defense official said. U.S. commanders will alter procedures and adopt countermeasures as necessary, he said.

Classified sections of the 30-page report provide a variety of sensitive information.

For example, it indicated the number and timing of insurgent attacks -- well over 100 along the Baghdad airport road in the half-year leading up to the checkpoint shooting. It named checkpoints that were especially susceptible to attack. It also included an assessment of insurgent bombing tactics and the U.S. ability to counter them, highlighting suicide car bombs as a threat that, once in motion, are extremely difficult to identify.

In terms of U.S. rules of engagement, the report described specific steps that soldiers are allowed to take in escalating the level of force to stop approaching vehicles. It outlined the different types of U.S. checkpoints, ranging from permanent, to short-term or "hasty," to "flying" roadblocks erected with little or no planning.

The report also disclosed the names of American soldiers and Italians in the incident, which the Pentagon had withheld, citing privacy.

The disclosure of the classified report was not intentional, said the U.S. defense official, who voiced concern that the Italian news media could view the inadvertent release as conspiratorial.