The U.S. military has obtained a DNA sample that would enable forensics experts to identify the bodies of deposed Iraqi president Saddam Hussein and his two sons if they are ultimately found, the nation's top battlefield commander said yesterday.

But Gen. Tommy R. Franks and his boss, Defense Secretary Donald H. Rumsfeld, said confirmation of Hussein's death would not mean the military's job in Iraq is finished, because U.S. forces continue battling small groups of diehard fighters and still must inspect thousands of suspected sites where chemical, biological or nuclear weapons may be present.

Speaking on television talk shows, both Franks and Rumsfeld said that several senior government figures had been captured, without disclosing the identities of those in custody. Their remarks followed a disclosure by U.S. officials in Washington that Hussein's half-brother, Barzan Ibrahim Hasan, had been apprehended late last week in northern Iraq.

Rumsfeld also repeated the administration's warnings to Syria, citing "unhelpful" behavior since the war in Iraq began. He said that members of Hussein's government are known to have fled to Syria and that busloads of Arab fighters have been interdicted coming into Baghdad from Syria.

"On one of the buses, they found something like several hundred thousand dollars and a number of leaflets that suggested that people would be rewarded if they killed Americans," Rumsfeld said on CBS's "Face the Nation."

Rumsfeld and Franks also said U.S. forces have encountered Syrian mercenaries and other foreign Arab fighters in Baghdad. "The government's making a lot of bad mistakes, a lot of bad judgment calls, in my view, and they're associating with the wrong people," Rumsfeld said.

President Bush, speaking briefly to reporters yesterday, also emphasized that "the Syrian government needs to cooperate" with U.S. forces.

Rumsfeld declined to comment on what type of action the Bush administration might take against Syria, saying it was not up to him to decide. Asked what the implication would be if Hussein turned up alive in Syria, Rumsfeld said: "Then Syria would have made an even bigger mistake."

Franks did not explain how U.S. forces had obtained a DNA sample that would enable them to identify the bodies of Hussein or his sons, Qusay and Uday. But one U.S. official in Washington said that Hasan could provide "a walking source of DNA." Because Hasan and Hussein share the same mother, DNA samples from both men would contain the mother's unique genetic signature. Scientists could use that information to compare tissue samples with bodies buried underneath the rubble of a building in the Mansour neighborhood of Baghdad bombed Wednesday by U.S. war planes in the belief that top Iraqi leaders were inside.

U.S. forces, acting on information from the CIA, captured Hasan near the Syrian border, the official said. Hasan, who was apprehended late last week, "had been estranged" from the Iraqi leader since 1995, when he stepped down as Iraq's interior minister and took the vague title of "adviser to the president."

In fact, said a senior government official, Hasan "was definitely not close to Hussein, and the Iraqi leader kept him on a short leash."

Hussein's government, including key Baath Party, security and intelligence officials who had been monitored by U.S. Special Operations and CIA teams, disappeared Wednesday, indicating they had prearranged an escape plan.

The vast majority of Hussein's inner circle remain at large and their whereabouts continue to be a perplexing mystery for intelligence officials charged with tracking them down.

Since the war began, U.S. forces have captured or killed only a few key leaders. Ali Hassan Majeed, Hussein's cousin, nicknamed "Chemical Ali" by defense officials, was hit in an airstrike and is the only confirmed death.

On Saturday, Hussein's top science adviser, Lt. Gen. Amir Saadi, turned himself over to U.S. military officials. He is a potentially valuable source of information about Iraq's weapons of mass destruction, but has already told his captors that Iraq does not possess chemical or biological weapons.

Both Franks and Rumsfeld rejected that assertion, saying they were confident U.S. forces would eventually find hidden caches of Iraq's chemical and biological weapons. Speaking on CNN's "Late Edition," Franks said that 2,000 to 3,000 sites will have to be searched for suspected chemical or biological weapons before a military victory can be declared.

Those sites must be searched and secured to ensure that "some small cell" of Hussein loyalists doesn't take those weapons out of Iraq or use them against U.S. forces inside Iraq, Franks said.

Searching those sites, eliminating pockets of resistance and securing Hussein's home town of Tikrit, the last major population center not yet under U.S. or British control, Franks said, could take weeks. And it could take many months more, he added, to stabilize the country, distribute humanitarian relief and create conditions that would enable the Iraqi people to "govern themselves."

Within days, however, Franks said he would probably travel to Baghdad to gauge conditions there for himself. "I'm not looking to have a victory parade in downtown Baghdad," Franks said. "I'm not looking to make some sort of a statement, but I am looking to have the best appreciation of what's going on in that country that I can have because it's my responsibility to do that."

On "Fox News Sunday," Franks explained that Baghdad, the Iraqi capital, has been subdivided into 55 or 60 security zones that U.S. forces are working to secure. In 10 or 15 of those zones, Franks said, U.S. forces expect to find groups of five to 25 "hardcore" Hussein loyalists or Arab fighters, as one Army unit did on Saturday night in the western part of Baghdad.

As troops work to secure Baghdad and other Iraqi cities, Franks said, they are finding it possible to quickly identify Iraqis with whom they can establish alliances, either because they are known to have been opponents of Hussein's government, or because they are seeking to return to work in order to cooperate with U.S. or British forces.

He noted on ABC's "This Week With George Stephanopoulos" workers in Iraqi's northern and southern oil fields have already contacted U.S. and British commanders and asked to return to work. "People in civil administration have already come to us and said, 'Well, we're ready to take charge of our destiny and go back to work,' " Franks said, expressing confidence that looting in Iraq's cities would soon begin to wane.

Rumsfeld also expressed confidence that conditions in Iraq would improve as U.S. forces wrap up combat operations and a team of "regional coordinators" headed by retired Army Lt. Gen. Jay M. Garner arrive in Iraq and begin establishing administrative control over government ministries.

"We have to . . . see that we provide the humanitarian needs for the people of that country," Rumsfeld said on "Face the Nation." "It's just terribly important that they have the water and the food and the medicines. And we've got an excellent group of people organizing and assisting, and the international community's participating."

Rumsfeld said that he had suggested to George Robertson, NATO's secretary general, that the 19-member European military alliance consider the contribution of peacekeeping forces. Rumsfeld said he has been advised that France, which opposed the war in Iraq, would oppose a peacekeeping role for NATO. "They're opposed to a lot of things," he said.

But if France sought to block NATO participation in NATO's 19-member North Atlantic Council, Rumsfeld said, the alliance could simply move the issue to its 18-member Defense Planning Committee, which does not include France, as it did when France objected in February to a formal request by fellow member Turkey for military aid to protect it in the event of a war in Iraq.

Rumsfeld later told reporters that Bush has already stated his desire to have the United Nations "play a role" in stabilizing and rebuilding Iraq. He said he didn't know what role U.N. officials could ultimately play, because France has indicated its opposition to "certain kinds of roles for the United Nations."

"But certainly I'm hopeful that they will be cooperative and supportive and helpful," he said.