The US army admitted Saturday that US soldiers mistakenly opened fire at a car carrying the freed Italian hostage, wounding her and killing an Italian secret service agent.

"Coalition Forces assigned to the Multi-National Force-Iraq fired on a vehicle that was approaching a Coalition checkpoint in Baghdad at high speed," the military said in a statement.

Kidnapped on Feb. 4, Giuliana Sgrena, a war reporter for Il Manifesto daily, was freed and handed over to three Italian agents on Friday.

The shooting happened when the agents were driving her to Baghdad Airport. Nicola Calipari was shot dead after he covered Sgrena with his body.

"Ms. Sgrena is being treated by Coalition Force medical personnel," the statement said without giving further details.

It said the incident was under investigation and more details would be provided when available.

Sgrena, 56, was seized by unknown gunmen on a Baghdad street. She appeared on TV two weeks after capture, pleading for her life and calling for withdrawal of Italian forces from Iraq.

US President George W. Bush had phoned Italian Prime Minister Silvio Berlusconi to express his regret over the incident and pledged a full investigation into the killing.

Italy is one of Washington's staunchest allies in the Iraq war, sending some 3,000 troops to Iraq.