|Abu Musab Zarqawi (undated State Dept. photo)|
In the recording, a voice alleged to be that of Abu Musab al-Zarqawi vowed to use al-Qaida in Iraq's new Omar Brigade to wipe out the Badr Brigade.
The Badr Brigade is the armed wing of the country's largest Shi'ite religious and political party, the Supreme Council for the Islamic Revolution in Iraq.
Formed in the 1980s in neighboring Iran to oppose Saddam Hussein, the force is made up mostly of Shi'ite Muslims, whom Zarqawi has denounced as being collaborators and traitors because they have formed military and political ties to the United States since the fall of Saddam Hussein.
In May, a leading Sunni-Muslim cleric in Baghdad publicly accused the Badr Brigade of killing Sunni clerics. Sunni mosques closed for three days in the capital in protest.
The accusation against the Badr Brigade angered many Shi'ites, who view Badr fighters as men committed to defending the Shi'ite people against oppressive Sunni Arabs like Saddam.
The political officer of the Supreme Council for the Islamic Revolution in Iraq, Saad Juad Qindeel, vehemently denies Sunni accusations that the Badr Brigade acts as a vigilante hit squad.
"What strategy Zarqawi is following is killing Shi'ites and putting the blame on Sunnis," he said. "And also killing Sunnis and trying to put the blame on Badr. And by doing that, he wants to ignite a sectarian conflict."
The al-Qaida in Iraq leader has long been accused by U.S. military and Iraqi officials of trying to provoke a sectarian war. Al-Zarqawi is also believed to be responsible for a string of attacks on foreign diplomats in recent days.
On Tuesday, his group took responsibility for Saturday's kidnapping of Egypt's highest-ranking envoy in Iraq, Ihab al-Sherif, in western Baghdad. In another statement posted Wednesday on the Internet, the group threatened to kill him because it said Egypt has allied with "Jews and Christians".
Gunmen also attacked diplomats from Bahrain and Pakistan Tuesday in the capital.
After the attacks, Pakistan announced it was moving its ambassador to Jordan until the security situation in Baghdad improved.
Iraqi government spokesman Laith Kubba says the attacks appear to be an attempt by Sunni extremists to prevent Arab and other Muslim countries from strengthening diplomatic ties with Iraq. He says his government is disappointed with Pakistan's decision to pull out.
"We are trying to make clear that this is exactly the sort of response these groups are seeking and if one yields to them, then they will be on the run all their lives," he said. "Without a question, leaving is sending the wrong message. We believe there is no additional risk currently."
The U.S. Embassy in Baghdad also urged calm. An embassy official told reporters that the United States believes it is important for the international community to show support for the Iraqis by establishing and maintaining a diplomatic presence in the country.
Bahrain, a key U.S. ally in the Gulf, responded swiftly, promoting its envoy, who was slightly wounded in Tuesday's attack, to the full rank of ambassador.