Iraq is cooperating with weapons inspections on the ground but needs to answer questions about its recent arms declaration, the chief U.N. weapons inspector said Friday.

Hans Blix, who heads the U.N. Monitoring Verification and Inspection Commission, charged with investigating Iraq's biological, chemical and missile programs, wouldn't confirm Iraqi claims that his inspectors hadn't found anything so far.

"We are spreading over the country and seeing more sites. There are also samples being taken and analyzed," he said.

Blix is to brief the council in fuller detail next Thursday, travel to Baghdad for meetings with Iraqi officials around Jan. 18 and then submit his first official report to the Security Council on Jan. 27.

In the meantime, Blix's office is working out details for conducting interviews with Iraqi scientists. The United States has been pressing hard for inspectors to begin questioning Iraqis who may have inside knowledge of Saddam Hussein's weapons programs.

"We are now examining a lot of names here. There will be interviews and we are deciding the modalities, the modes and the place," Blix said.

Blix's commission hasn't conducted any formal interviews since inspections resumed five weeks ago after a four-year break. The International Atomic Energy Agency has conducted two interviews so far, both while Iraqi government officials were present, U.N. officials said.

On Thursday, President Bush said he was "hopeful we won't have to go to war," but was skeptical about Saddam's willingness to voluntarily rid his country of nuclear, chemical and biological weapons.

One reason Bush gave for his doubts were reports of U.N. weapons inspectors' interviews with Iraqi scientists with "minders in the room."

Blix and Mohamed ElBaradei, the IAEA chief whose agency is investigating Iraq's nuclear programs, will travel together to Baghdad in the third week of January to meet with their Iraqi counterparts.

On Friday, Blix said the Iraqis were cooperating with inspectors on the ground. But there are "questions that have arisen as a result of (Iraq's) long declaration ... and we'd like to follow up some of those," he said.

Blix's inspectors are charged with investigating Iraq's biological, chemical and missile programs.

Blix told the Security Council last month that Iraq's declaration didn't include a list of nutrients Baghdad acquired for producing biological warfare agents, including anthrax.

He also said Iraq's reporting of its destruction of anthrax supplies from 1988 to 1991 "may not be accurate." Iraq declared earlier that it produced 2,210 gallons of anthrax, but inspectors have estimated it could have been as much as 6,240 gallons. Baghdad hasn't accounted for the destruction of everything that was produced, he said.

Iraq also didn't provide sufficient information about its production of missile engines, 50 conventional warheads it claims were destroyed but haven't been recovered, 550 mustard gas shells declared lost after the 1991 Gulf War, production of the deadly VX nerve agent, and its destruction of biological warfare agents, he told the council on Dec. 19.

On Friday, three teams of inspectors fanned out across Iraq in search of illicit weapons. Missile inspectors visited a plant outside Baghdad and tagged equipment Iraq had manufactured in the past four years. A second team visited a former munitions depot, while a chemical team inspected a chemicals plant east of the Iraqi capital, inspectors said.