ROME, March 9: The United States must assume responsibility for the 'friendly fire' killing of an Italian intelligence agent in Iraq in order to put the incident behind the two allies, the Italian prime minister said on Wednesday.

"Only a frank and reciprocal recognition of eventual responsibility is the condition for closure of the incident which was so irrational to us and that caused us so much sorrow," Prime Minister Silvio Berlusconi told the Senate.

US soldiers opened fire on agent Nicola Calipari's vehicle for 10 seconds to 15 seconds as he was taking newly freed hostage Giuliana Sgrena to Baghdad airport, Mr Berlusconi said, immediately killing Calipari and wounding the kidnap victim.

Italy had made all necessary contacts with US authorities for safe passage, advising military at the airport as Ms Sgrena was en route, Mr Berlusconi said. He contradicted preliminary accounts from the US military that it had no knowledge of the rescue mission.

Still one of the strongest supporters of US foreign policy in Europe, Mr Berlusconi said he was pleased the United States had accepted his request to participate in an investigation of last Friday's shooting.

"Our friendship with the United States is strong and loyal, and we have the duty to demand from them the utmost truth," Mr Berlusconi said, winning a standing ovation from all political parties at the end of his speech. A senior Italian military official and diplomats will join the probe, which the US military says should be concluded in one month.

TWO VICTIMS: Even in the divisive world of Italian politics, Mr Berlusconi has won universal praise, including from adversaries, for his tough approach to the incident - summoning the US ambassador to government offices.