Italian Foreign Minister Gianfranco Fini Tuesday disputed the US explanation of killing an Italian intelligence officer in Iraq and demanded the US military conduct thorough investigations.

Fini told parliament that the car in which intelligence officer Nicola Calipari was escorting freed journalist Giuliana Sgrena was not driving too fast and was not ordered to stop by US troops, contrary to the claim of the US military.

"The car was traveling at a speed that couldn't have been more than 40 km per hour," he said.

Fini also dismissed Washington's claim that lack of communication had been partially to blame for the death of the Italian agent, saying that Calipari had made "all the necessary contacts with US authorities in Baghdad."

The foreign minister, however, disagreed with allegations made by the freed journalist who said Sunday that the shooting might be intentional as "everyone knows that the Americans don't want hostages to be freed by negotiations."

"It was an accident," Fini said, adding that Sgrena's hypothesis that the shooting was an ambush was groundless.

The minister has called on the US military to investigate the shooting fully and punish any soldiers found responsible for the death of Calipari who was buried Sunday in Rome.

While Fini challenged the US explanation about the shooting, the US commander of multinational forces in Iraq said Tuesday that the United States and Italy will jointly investigate the incident and the probe will last three to four weeks.

"My expectation is it will be a joint investigation" and "these investigations normally take three to four weeks to complete," General George Casey said at a press conference at the Pentagon.

Casey, who was in Washington for meetings at the Pentagon and on Capitol Hill, said the investigation was headed by Brigadier General Peter Vangjel.

The general said he had no information to indicate Italian officials had told US forces in advance that the Italian journalist, Giuliana Sgrena, had been released.

"I personally do not have any indication of that, even on a preliminary basis," he said.

Calipari was killed last Friday in Iraq when American troops opened fire on his vehicle as he was escorting Sgrena to Baghdad airport after a month in the hands of kidnappers.

In a statement issued later in the day, the US military said troops opened fire because Calipari's car was traveling at high speed and refused to stop at a check point.

However, Sgrena, who was wounded in the incident, said Sunday that it was possible they were targeted deliberately because the United States opposes Italy's policy of negotiating with kidnappers.

Also on Sunday, a senior White House official further explained the shooting as a "horrific accident" and promised a full investigation.

"This is a horrific accident, on which President Bush personally called Prime Minister Berlusconi to offer his condolences, as well as to make sure that there is a full investigation, so we're able to understand the very facts that are now being discussed," White House counselor Dan Bartlett said on CNN's "Late Edition."

"As you know, in a situation where there is a live combat zone, particularly this road to the airport has been a notorious area for car bombs, that people are making split-second decisions, and it's critically important that we get the facts before we make judgments," Bartlett said.

(Xinhua News Agency March 9, 2005)