"It's a very aggressive effort right now to address this hostage situation," he said. "I can't say much more than that."

He said FBI personnel along with law enforcement agencies from the international community were involved.

He said all of the coalition members were developing intelligence to identify the hostage-takers and find where the hostages were being held.

One of four Italian hostages being held in Iraq has been killed, Italian Foreign Minister Franco Frattini announced early Thursday, while Japanese officials tried to confirm reports two more of their nationals had been kidnapped.

French journalist Alexandre Jordanov, who was taken hostage south of Baghdad three days ago, was freed, a French diplomat said.

But that left about 40 other foreigners still being held hostage, coalition officials have said, amid a wave of kidnappings designed to destabilise the US coalition.

Frattini named the dead hostage as Fabrizio Quattrocchi, 35, from Genoa.

The kidnappers threatened to kill the other three hostages "one by one if their demands were not taken into account," Al-Jazeera said.

Berlusconi, a major ally of the United States in Iraq, had said Tuesday there was "no question" of Italy withdrawing its 3,000-strong military force from the country.

Meanwhile Yukihisa Fujita of the opposition Democratic Party of Japan, speaking in Amman, said two more Japanese had been kidnapped.

Meanwhile, Russia started to evacuate former Soviet citizens from Iraq yesterday amid a wave of kidnappings targeting foreigners, a diplomat said.

"A first group of between 150 and 200 people left aboard a plane this morning at 7:00 am (0300 GMT) heading to Moscow," said diplomat Dimitri Iline.

Five Ukrainians and three Russians were held hostage for around 24 hours earlier this week before being released without harm.

US-led coalition officials have said around 40 foreigners are being detained by Iraqi insurgents who are demanding the withdrawal of international troops from the country.

Earlier, three Russian planes being sent to evacuate hundreds of former Soviet citizens currently working in Iraq left Moscow last morning for Baghdad, Russian news agencies reported.

The emergencies ministry planes took off in succession from an airport outside the Russian capital beginning at 10:00 am (0600 GMT), Interfax and RIA Novosti reported.

Another four flights are planned for Friday to evacuate those of the more than 800 former Soviet nationals working in Iraq for Russian companies who want to leave the war-torn country.

Out of those eligible to be evacuated, 553 are Russian nationals and 263 are nationals of other former Soviet republics.

Russia's top contractor in Iraq, the Technoprom energy firm, is evacuating all of its 370 employees from the country.

The move followed the brief kidnapping earlier this week of nine employees with another Russian contractor in the country, Interenergoservis, amid a spate of foreigner kidnappings by insurgents.