In an interview with CNN in Mosul, Iraq, General John Abizaid, the commander of US Central Command, which covers Iraq, said that while most insurgents appear to be Iraqis, "The percentage of foreign fighters over the past several months seems to have increased."

He also said the insurgents' ranks likely include "former Baathist criminals."

"It seems to be pretty well established that they tend to cross over from Syria, although we know that there have been some infiltrations from the Saudi border, there have been some from the Iranian border," Abizaid said.

"The Syrians are not doing everything we've asked them to do," Abizaid said, adding that Syria's intelligence services are not being aggressive enough in dismantling "facilitation cells" inside Syria.

In a separate CNN interview, George Casey, the commanding US general of the Multi-National Force in Iraq, told the news network that current insurgent assaults were running at between 50 and 60 attacks a day.

"They (insurgents) are able to maintain the level of violence between 50 and 60 attacks a day," Casey said.

"And the four provinces where the insurgency is still capable is out west, near Fallujah in Anbar province, in the Baghdad area, and Saladdin, which is in the center of the country, around Saddam's home town, and up north, in the Mosul area," Casey said.

Casey said the insurgency had not been broken yet.

"Not yet. What it means to me is that they're not nearly as strong or as capable as some people thought they were prior to the elections," he said of the insurgents.

"Since the elections, the Iraqi security forces have gotten more involved, and the Iraqi people have gotten more involved in giving us tips, telling us where insurgents are and where insurgent weapons storage sites and things like that are," Casey said.

Asked for an update on the ongoing US manhunt for Iraq's most-wanted insurgent, the Al-Qaeda linked Jordanian Abu Masab Al-Zarqawi, Abizaid said Al-Zarqawi's followers were certainly operating in western Iraq.

"I think ... you well understand that a big military organization like the US military are pretty good at pressuring the (insurgent) networks, and that is what we're doing.

"A single manhunt is a difficult thing. Over time, we keep finding out more and more about his organization, we take more people out of it, and his time is running out," Abizaid predicted.

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