An aide of the head of Al Qaeda in Iraq was arrested last week, and U.S. and Iraqi forces killed or captured more than 600 suspected members of the terrorist group in September, the top U.S. military spokesman in Iraq said Wednesday.

The associate of Abu Ayyub al-Masri was captured in raids carried out Sept. 28 in Baghdad that also seized 31 other Al Qaeda suspects, Maj. Gen. William B. Caldwell told reporters.

He said the associate had worked as al-Masri's driver and personal assistant and had been involved in planning bombings in the capital.

"We feel very comfortable that we're continuing to move forward very deliberately in an effort to find (al-Masri) and kill or capture him," Caldwell said.

During September, U.S. and Iraqi forces killed 110 suspected Al Qaeda members and detained another 520, Caldwell said, calling it "a significant upturn over August." He did not say how many were captured or killed the previous month.

Fifty of those killed and 16 of those detained were foreign fighters, he said.

Al-Masri, believed to be Egyptian, took the leadership of Al Qaeda in Iraq, one of the country's deadliest terror groups, after the death of his predecessor, Abu Musab al-Zarqawi, in a U.S. airstrike north of Baghdad in June.

In early September, Iraqi officials announced the arrest of Hamed Jumaa Farid al-Saeedi, who they said was a top deputy of al-Masri.

"We're obviously gleaning some key critical information from those individuals and others that have been picked up and detained that are going through the interrogation process," Caldwell said.

On Sunday, the Iraqi government released a captured video of al-Masri, showing him demonstrating how to build a bomb in a tanker truck. The video was the first to show the militant leader's face, although U.S. and Iraqi military officials have shown photos of him.

Caldwell said he hoped the release could generate tips that would lead to al-Masri's capture.

He said coalition forces already conducted one raid based on a tip after the video's release, but it turned out to be a false lead.

"I think the fact that his face has been so very visibly displayed on TV cameras will, in fact, probably be very much of assistance," Caldwell said.

In the video, al-Masri, wearing a white T-shirt, is seen talking to the camera as he moves beside boxes and coils of wire, apparently giving instructions how to put together a car bomb. His hair was cut short and he wore glasses and had a mustache but no beard. No one else appeared in the video.

If nothing else, Caldwell said, the video "demonstrates that al-Masri's intent is to kill and injure Iraqi civilians."