THOUSANDS of Italians filed past the coffin of an intelligence agent killed by American troops in a bungled hostage rescue as the White House expressed regret yesterday over the “horrific accident”.

As crowds paid homage to the body lying in state at the Tomb of the Unknown Soldier, President Ciampi called on Washington to clarify what happened.

The freed hostage, Giuliana Sgrena, 56, a left-wing journalist, claimed that US troops may have deliberately opened fire because of US opposition to the Italian policy of negotiating with hostage-takers in Iraq.

She described how Nicola Calipari, the intelligence agent, had shielded her as a US patrol fired on them and how he had died almost instantly.

The American command in Baghdad insists that it was not informed of the rescue operation and that the car carrying Signora Sgrena was travelling at high speed and had failed to stop at a checkpoint.

“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,” Dan Bartlett, the White House communications chief, said yesterday.

Gianfranco Fini, the Italian Foreign Minister, described the shooting as simply “a macabre mockery of fate”. Nevertheless, prosecutors in Rome opened a “manslaughter inquiry”.

Reports allege that Signor Calipari negotiated a ransom of between $6 million and $8 million (£3.1 million and £4.1 million). Asked whether a ransom was paid for Signora Sgrena, Giovanni Alemanno, the Agriculture Minister, said that it was very probable.

Signor Calipari, who was married with two children, will be given a state funeral today. A post-mortem examination indicated that he had been killed by a single bullet to the head.

However, Signora Sgrena, who was hit in the left shoulder, said that “300 to 400” bullets had been fired “without any justification” by a US patrol as the unmarked car approached Baghdad airport, where American and Italian intelligence officers were waiting for them.

In her newspaper, Il Manifesto, Signora Sgrena said that her Iraqi kidnappers had told her to “be careful because the Americans do not want you to go back”. At first she had dismissed this, but the warning “came back to me as we came under a hail of fire”. She said in a television interview: “Everyone knows the Americans are against negotiating with hostage-takers, so I cannot exclude the possibility that they targeted me.”

She said that she and her secret service escort were speaking on their mobile phones when the firing broke out. The driver shouted that they were Italian. “Nicola Calipari dived on top of me to protect me and immediately, and I mean immediately, I felt his last breath as he died,” she said.

According to the US military, the troops used hand signals, flashing lights and warning shots to get the car to stop.

But Signora Sgrena said “there was no bright light, no signal, and no checkpoint — it was a patrol”. She said that the car had already passed the last US checkpoints and was traveling at “normal speed” within 700 metres of the airport. Italian officials said that American forces had been fully informed of the rescue.

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