Non-Iraqi Arabs belonging to Al Qaeda are ready to carry out terrorist acts against coalition forces in Iraq, an Iraqi opposition spokesman told Fox News Saturday.

Nabeel Masawi of the Iraqi National Congress said via telephone from Iraqi Kurdistan that Al Qaeda operatives were in the region of Najaf and Karbala in central Iraq.

The INC also issued a press release stating, in part, that there existed "an agreement made between [Usama] Bin Ladin (sic) and Saddam to allow Bin Ladin's men to take control of the [Najaf and Karbala] area if they can defend it."

Masawi said the information came from a reliable source within Iraqi intelligence.

On Saturday, four American soldiers were killed when a homicide bomber driving a taxi cab blew himself up outside Najaf.

The killer stopped his cab close to a military checkpoint, waved for help, and then detonated his explosives as the four soldiers approached.

Iraqi state television later identified the attacker as a junior army officer, and Iraqi President Saddam Hussein awarded him two posthumous medals.

Masawi disagreed, saying, "We know for a fact that the person who carried out this mission is a Saudi national who moved to Iraq in recent months after [he was] in Afghanistan."

"Expect some more of these homicide missions to occur in the next few days," Masawi added.

A Scottish newspaper reported Friday that British military sources said Al Qaeda might also be active near Basra in southern Iraq.

"The information we have received from POWs today is that an Al Qaeda cell may be operating in Az Zubayr. There are possibly around a dozen of them," a British military source told The Scotsman.

The INC also said Kurdish groups confirmed Friday that the taxi bomber who killed an Australian journalist in northern Iraq a week ago was a Saudi national.

The attack happened at a checkpoint near the area controlled by Ansar al-Islam, a small Kurdish Islamic fundamentalist group that the United States and the secular Kurdish groups say is linked to Al Qaeda.

The U.S. has said Ansar al-Islam also receives support from the Iraqi government in Baghdad, while the Kurds maintain its main support comes over the Zagros Mountains from Iran.

Opposition sources have said they have information dating back more than year that there were non-Iraqi Arabs being trained at a camp in Salman Pak, about 30 miles south of Baghad.

A defector apparently told the opposition that Fedayeen Saddam, state paramilitary fighters, were being trained in one section of the camp, and Arab foreigners in another part.

"Iraqi intelligence officers traveled to Afghanistan in 1998," Masawi told Fox News. "They met Usama bin Laden and some of his lieutenants. Financial help was offered and was received by Al Qaeda from Saddam Hussein's intelligence service."

The Iraqi National Congress was formed in 1992 as a coalition of the major Iraqi opposition groups, including Sunni and Shiite Islamist and secular factions as well as the two major Kurdish parties. It is based in London but moved many operations to Iraqi Kurdistan recently in anticipation of a U.S. led-invasion.

The INC press release noted that Najaf and Karbala were the two holiest cities of Shiite Islam — and that their falling under Al Qaeda control would place them and their populations in great danger.

Al Qaeda and its leader Usama bin Laden are extremist Sunni Muslims who tend to view Shiites as misguided at best and heretics at worst.

Shiites comprise about 60 percent of the Iraqi population, and three-quarters of the country's Arabs, but are politically marginalized. The ruling clique around Saddam Hussein are mostly Sunni Arabs, many from Saddam's home city of Tikrit.

At the end of the first Persian Gulf war in 1991, the Shiites of Basra rose up against Saddam Hussein, but the U.S. assistance they were expecting never materialized and the revolt was suppressed as bloodily as it had begun.

Fox News' Teri Schultze and the Associated Press contributed to this report.