Three Japanese hostages were freed Thursday by their Iraqi captors. But violent acts continued elsewhere in Iraq, including the slaying of an Iranian diplomat in Baghdad.

CTV.ca News Staff

Three Japanese hostages were freed Thursday by their Iraqi captors. But the joy of the moment was overshadowed by violence elsewhere.

Gunmen killed a high-ranking Iranian diplomat in Baghdad. Khalil Naimi was shot in the head while in his car near the Iranian embassy, Foreign Ministry official Mohammad Nouri told The Associated Press in Tehran.

It is unclear if the killing is linked to Iranian efforts to negotiate a resolution to the U.S. standoff with radical cleric Moqtada al-Sadr.

The three freed hostages -- two aid workers and a journalist -- were shown on Al Jazeera television meeting a representative of the Muslim Clerics Association. They were captured a week ago by a group who threatened to kill them unless Tokyo withdrew its troops from Iraq.

The woman, Nahoko Takato, was shown weeping into her hands. Another aid worker, Noriaki Imai, shook hands with one of the members of the association. The third released person was journalist Soichiro Koriyama, who was nearby in the Baghdad office.

Japan is still investigating whether reports about the abduction of two journalists is true.

News of the release comes shortly after Italian officials confirmed that one of the four Italian security guards abducted in Iraq has been killed -- the first known hostage to be executed since the kidnappings of civilians began late last week.

Italian Foreign Minister Franco Frattini confirmed early Thursday that Fabrizio Quattrocchi had been killed. He said the Italian ambassador to Qatar had viewed a tape of the killing.

The kidnappers had given the tape to Al Jazeera, which said it was too "too gruesome" to air.

There kidnappers are now threatening to kill the other three Italian hostages if Italy does not withdraw its troops from Iraq, according to Al Jazeera.

Prime Minister Silvio Berlusconi vowed not to give in and to keep Italian forces in Iraq.

"They have destroyed a life. They have not cracked our values and our efforts for peace," he said in a statement read on state television.

The four Italian security guards were abducted on Monday by a previously unknown group calling itself the "Green Battalion."

Quattrocchi, 36, had been in Iraq since November. He was being paid $12,500 US a month to guard oil pipelines, and was saving the money to buy a house with his fiancee.

Throughout Iraq, insurgents have kidnapped more than 40 foreigners in the past week, including a Canadian aid worker, Fadi Fadel. He is still missing.

Other developments:

• American experts are conducting tests on four bodies found west of Baghdad, to determine if they are the remains of private U.S. contractors who have been missing since Friday.
• Russia is beginning to evacuate its nationals from Iraq due to concerns over the spate of civilian kidnappings. Earlier this week, eight Ukrainian and Russia contractors were abducted, and then released 16 hours later.
• An audio tape purported to be by Osama bin Laden is offering European nations a "truce" if they withdraw their troops from Muslim countries. It has been rejected.
• France and the Philippines are also urging their citizens to leave. However, President Gloria Macapagal Arroyo said she would not withdraw any troops.