BAGHDAD (Reuters) - The U.S. administrator for Iraq arrived in Baghdad on Monday to begin the huge task of repairing devastation caused by the war to oust Saddam Hussein.

Retired general Jay Garner flew in from Kuwait to assess needs in the battered capital as pressure mounted from regional nations and Europe for Washington quickly to make way for the United Nations in the rebuilding of Iraq.

U.S.-led troops, their offensive role all but over, widened the dragnet in their search for dozens of leading members of the ousted government, seizing Saddam's scientific research minister Adbul-Khaleq Abdul-Ghafur.

The opposition Iraqi National Congress said Saddam's one surviving son-in-law -- two others were executed in the 1990s after defecting -- had surrended to them and would be handed over to U.S. forces.

The fate of Saddam himself and his sons Uday and Qusay remained a mystery 12 days after U.S.-led forces pushed into the center of Baghdad, ending Saddam's 24-year reign.

In Moscow, a senior foreign ministry official said Russia would insist on U.N. arms inspectors declaring Iraq free of weapons of mass destruction before sanctions could be lifted.

The United States is pushing for the quick scrapping of the 12-year-old sanctions but Russia, France and some other countries fear that once they are gone the United Nations will have no more leverage over Iraq's future.

NO WEAPONS FOUND

President Bush launched the invasion of Iraq on March 20, saying he wanted to oust Saddam and rid the country of chemical and biological weapons, but so far no trace has been found of such arms.

Iraq denied having weapons of mass destruction.

Itar-Tass news agency quoted the unnamed Russian foreign ministry official as saying U.N. weapons inspectors Hans Blix and Mohamed ElBaradei should be allowed to return and quickly finish their work.

"This could be done within a couple of weeks as it is obvious that there are no such weapons there," the official said.

Ahmad Chalabi, founder of the Iraqi National Congress and a favorite of the Bush administration, told BBC Radio the United Nations should have only a limited role in getting Iraq back on its feet.

"The United Nations cannot play a significant role in Iraq because it has little credibility in Iraq," he said.

Chalabi said his intelligence reports indicated Saddam was still in Iraq, contrary to speculation that he might have fled to neighboring Syria.

Senior U.S. officials have accused Damascus of harboring fugitive members of Saddam's inner circle, but Bush himself made conciliatory remarks about Syria on Sunday, saying there were "positive signs" it would deny sanctuary to fleeing Iraqis.

The INC said Saddam's son-in-law Jamal Mustafa Sultan al-Tikriti had surrended to them along with a top official of Saddam's secret police, Khaled Abdallah, after both returned from Syria. It said Jamal's brother Kamal, the head of Saddam's personal guard, was still in Syria.

RANSACKED HOSPITAL

Garner, head of the Office of Reconstruction and Humanitarian Assistance (ORHA), began his four-day tour with a visit to Baghdad's Yarmuk hospital, which has been ransacked.

Zayed Abdul Karim, the head of the hospital, led Garner through dark, dusty corridors littered with broken glass and showed him wards stripped by looters of everything except beds.

The hospital has had no electricity for two weeks since Baghdad's power was cut during the U.S. air bombardment.

The lights came back on in parts of eastern Baghdad on Sunday night, hours before Garner's arrival.

Garner said his priority was to restore basic services such as water and electricity "as soon as we can." Asked what the greatest challenge was, he said: "Everything is the challenge."

Garner said he wanted to get the job done and leave as soon as possible.

"What we need to do from this day forward is to give birth to a new system in Iraq. It begins with us working together, but it is hard work and it takes a long time. We will help you as long as you want us to," he said.

Some doctors at the hospital were skeptical about U.S. intentions. "I want to cry, because these are only words," a doctor who gave her name as Iman said after listening to Garner.

"Saddam Hussein was an unjust ruler, but maybe one day we could have got rid of him, and not had these foreigners come in to our country."

Highlighting the confusing power vacuum that has prevailed since Saddam was toppled, a U.S. official said Washington did not recognize Mohammed Mohsen al-Zubaidi, a former exile who has declared himself governor of Baghdad.