The U.S. military, however, disputed claims that 16 passengers on a bus hit by a roadside bomb in southern Iraq were killed, saying no one died in the attack, which was targeting a passing military convoy.

It was not immediately clear why there was a discrepancy in the death toll.

The military announced that three American soldiers were killed in a roadside bombing north of Baghdad on Monday, bringing to eight the number of troops who died that day. The last time so many U.S. military personnel were killed in Iraq was Sept. 10, when 10 died.

Bloodshed has increased recently, despite what the military said has been a 60 percent drop in attacks across Iraq since June. Last Thursday, two massive bombs killed 68 people in Baghdad's Karradah neighborhood. On March 3, two car bombings killed 24 people in the capital.

According to an Associated Press count, at the height of unrest from November 2006 to August 2007, on average approximately 65 Iraqis died each day as a result of violence. As conditions improved, the daily death toll steadily declined. It reached its lowest point in more than two years on January 2008, when on average 20 Iraqis died each day.

Those numbers have since jumped. In February, approximately 26 Iraqis died each day as a result of violence, and so far in March, that number is up to 39 daily. These figures reflect the months in which people were found, and not necessarily — in the case of mass graves — the months in which they were killed.

Military spokesman Rear Adm. Gregory Smith said Sunday that recent violence should not be taken as evidence of "an increase or a trend of an increase."

"I think we need to continue to look at historically what has happened over the last year to really put in perspective a one-week or two-weeks' worth of activity inside Baghdad," Smith said.

But Smith, in what has become a military mantra of caution, also noted that "on any given day, al-Qaida and other extremist groups are still very much disposed toward handing out violence indiscriminately to achieve whatever means and ends they hope to achieve with those attacks."

While al-Qaida in Iraq is Sunni, Shiite extremists with alleged ties to Iran are also believed to have carried out attacks.

In a statement Wednesday, the military also said an American soldier died Tuesday after his patrol was hit by a roadside bomb near Diwaniyah, 80 miles south of Baghdad. Two other soldiers were wounded in the blast.

Tuesday's attack on the bus traveling from Najaf to Basra killed 16 civilians and wounded 20, said Dr. Hadi Badr al-Riyahi, head of the provincial health directorate. He added that the Nasiriyah and Suq al-Shiyoukh hospitals received 10 killed and 10 injured. Others were taken to facilities in Basra.

A local policeman said on condition of anonymity, as he was not authorized to speak to the media, that 16 were killed and 22 injured. The assistant bus driver, who identified himself only as Mohsen, also said 16 people were killed.

But Maj. Brad Leighton, a military spokesman in Baghdad, disputed that claim, telling The Associated Press only one coalition soldier and one Iraqi civilian were wounded in the attack about 50 miles south of Nasiriyah, which sits 200 miles southeast of Baghdad.

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