U.S. soldiers rest today in a house in Ramadi, west of Baghdad. Thousands of U.S. and Iraqi troops pushed into an eastern section of Ramadi, one of Iraq's most violent cities, the latest step in a campaign to gradually bolster their presence in city neighborhoods that for months have largely been under insurgent control.

BAGHDAD, Iraq — An umbrella group that includes al-Qaida in Iraq claimed in a Web statement today that it had kidnapped two U.S. soldiers reported missing south of Baghdad.

There was no immediate confirmation that the statement was credible, although it appeared on a Web site often used by al-Qaida-linked groups. U.S. officials have said they were trying to confirm whether the missing soldiers were kidnapped.

"Your brothers in the military wing of the Mujahedeen Shura Council kidnapped the two American soldiers near Youssifiya," the group said in a statement posted on an Islamic Web site.

The Web site did not name the soldiers.

The soldiers were reported missing Friday after insurgents attacked a checkpoint. The Defense Department identified the missing men as Pfc. Kristian Menchaca, 23, of Houston, and Pfc. Thomas L. Tucker, 25, of Madras, Ore.

The U.S. military said today it has intensified its search for the missing soldiers, with more than 8,000 Iraqi and U.S. troops deployed across the volatile area south of Baghdad where the men were attacked.

U.S. spokesman Maj. Gen. William Caldwell also said the military has killed three suspected insurgents and detained 34 others in fighting that left seven U.S. servicemen wounded during the search that began Friday evening.

Fighter jets, helicopters, unmanned drones, boats and dive teams are being used to find the two men who disappeared an attack on their checkpoint that left one of their comrades dead, Caldwell said.

Ahmed Khalaf Falah, a farmer who said he witnessed the abduction Friday, also told The Associated Press that the two soldiers had been captured by seven masked gunmen who were heavily armed during the attack near Youssifiyah, about 12 miles south of Baghdad.

The town is in the "Triangle of Death," a predominantly Sunni region that has been the scene of frequent ambushes of U.S. soldiers and Iraqi troops.

Insurgents also continued to defy a security crackdown in Baghdad, although violence appeared to have ebbed somewhat after several bloody attacks in recent days.

A parked car bomb struck an Iraqi army convoy near a busy Baghdad square today, killing five people, including four Iraqi soldiers, and wounding nine passers-by, Lt. Ahmed Muhammad Ali said. A policeman also was gunned down in a drive-by shooting in western Baghdad.

In Friday evening's attack that left the two Americans missing, the U.S. military has said that soldiers at a nearby checkpoint heard small-arms fire and explosions, and a quick-reaction force reached the scene within 15 minutes. The force found one soldier dead but no signs of the other two.

The three were assigned to the 1st Battalion, 502nd Infantry Regiment, 2nd Brigade, 101st Airborne Division (Air Assault), Fort Campbell, Ky.

The Defense Department said Spc. David J. Babineau, 25, of Springfield, Mass., was killed.