The U.S. military is performing DNA tests on a slain militant to determine if he is the leader of Al Qaeda in Iraq, but U.S. and Iraqi officials said Thursday it did not appear that Abu Ayyub al-Masri had been killed.

Meanwhile, U.S. Secretary of State Condoleezza Rice made a surprise visit to Baghdad, saying she will tell its leaders they have limited time to settle political differences spurring sectarian and insurgent violence. (Full story)

Car bombs, as well as other explosions and shootings, killed 34 people across the country Wednesday. At least 21 U.S. soldiers have been killed since Saturday, a disproportionately high number. Most of the casualties have been in Baghdad amid a massive security sweep by American and Iraqi forces that has been going on since August.

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Reports that al-Masri, also known as Abu Hamza al-Muhajer, had been killed surfaced after a raid Tuesday that killed four terror suspects in the western Iraqi town of Haditha.

U.S. forces initially "thought there was a possibility al-Masri was among them," Lt. Col. Barry Johnson said. But he said it did not appear the terror chief was killed.

"We have no reason to believe that we've killed al-Masri," Johnson told the Associated Press. "We are doing DNA testing to completely eliminate the possibility that this would be al-Masri, but we do not believe it is."

The statement came four days after Iraq's national security adviser, Mouwafak al-Rubaie, said U.S. and Iraqi forces were closing in on al-Masri.

But chief U.S. military spokesman Maj. William B. Caldwell was more skeptical on Wednesday.

"I'd love to tell you we're going to get him tonight," he told reporters. "But, obviously, that's a very key, critical target for all of us operating here in Iraq. ... We feel very comfortable that we're continuing to move forward very deliberately in an effort to find him and kill or capture him."

Caldwell said a driver for al-Masri had been captured in a Sept. 28 raid in Baghdad, the second figure close to the Al Qaeda in Iraq chief to be captured that month.

"We're obviously gleaning some key critical information from those individuals and others that have been picked up," he said, adding that 110 Al Qaeda suspects were killed and 520 detained in September.

Johnson would not say what kind of a DNA sample existed that tests of the body might be compared to, but said "we're confident we will be make a positive I.D., or not, when the time comes."

The process "can take weeks to resolve," Johnson said.

Iraqi government spokesman Ali al-Dabbagh and Defense Ministry spokesman Qassim al-Moussawi expressed even more certainty that the dead man was not al-Masri.

"The body belonged to someone else," said al-Dabbagh, without identifying the slain militant. "The DNA check will be completed" to make sure, he said.

In violence Thursday, a car bomb exploded in the mainly Shiite neighborhood of Hurriyah in Baghdad, killing two people and wounding two more, police 1st Lt. Thaer Mahmoud said.

Another bomb struck a group of laborers waiting for work at a downtown square in the capital, killing two and wounding 26, Mahmoud said.

The province of Diyala, an increasingly violent region north of Baghdad, saw a string of attacks early Thursday. Bombings and shooting in and around the province's capital Baqouba left seven dead. Iraqi officials have warned of increasing Al Qaeda presence in Diyala.

Baghdad has been torn by escalating violence over past weeks, a deadly combination of Sunni insurgent attacks and sectarian killings between Shiites and Sunnis. At least 21 U.S. soldiers have been killed since Saturday, most in Baghdad amid a massive security sweep by American and Iraqi forces that has been going on since August.

Iraqi Prime Minister Nouri al-Maliki vowed in comments to Iraqi state TV that the country is in the final stage of "confronting the security challenge" and that security would be achieved "within the two or three months to come."

Al-Masri, whose pseudonym means "the Egyptian," is believed to have taken over Al Qaeda in Iraq after Jordanian-born Abu Musab al-Zarqawi was killed June 7 in a U.S. air strike in Diyala province.

Iraqi intelligence knows the militant's real name and has samples of his fingerprints for comparison, said defense spokesman al-Moussawi, who refused to give the real name.

U.S. officials said al-Masri joined an extremist group led by Al Qaeda's No. 2 official Ayman al-Zawahri in 1982. He joined Al Qaeda training camps in Afghanistan in 1999 and trained as a car bombing expert before traveling to Iraq after the U.S.-led invasion in 2003.

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