ATHENS -- Chief UN weapons inspector Hans Blix said Tuesday Iraq had still not answered a great many questions about its alleged weapons of mass destruction.

"We feel the declaration (by Iraq to the United Nations) has not answered a great many questions of the past which still remain open. (Our views) have not changed on that," Blix told Reuters Television shortly before leaving Athens for New York.

On January 27, Blix, who has just completed a two-day visit to Iraq, will deliver a crucial report to the UN Security Council on Baghdad's compliance with searches for any nuclear, biological or chemical weapons it may be holding.

The report is expected to play a key part in any U.S. decision to attack Iraq.

Speaking of his trip to Baghdad, Blix said Iraqi refusal to allow American U2 spy planes to take part in searches was a setback.

"We did not see acceptance of everything we want to do. I think we have some way to go," Blix said. "We did not get acceptance of the U2 planes...and there are some other question marks."

Iraq wants to accompany the U2's with its own aircraft, but would be prevented from doing so if the weapons inspectors flew to the north or south of the country because of no-fly zones patrolled by U.S. and British planes since 1991.

Amir al-Saadi, an adviser to President Saddam Hussein, told Blix U.S. and British air sorties in those regions must stop for Iraq to allow the U2 flights. Explaining why U2 flights were important Blix said: "Satellites can't loiter over an area. If you have inspections in an area, a U2 can hover over it."

While Blix flies to New York, head of the International Atomic Energy Authority Mohamed Elearadei, who accompanied him to Baghdad, was due to travel from Athens later Tuesday to his headquarters in Vienna.

Monday, Elbaradei told reporters in Athens the inspections in Iraq were "midcourse," suggesting he and Blix believed more time was needed before a full judgment could be given on Iraqi compliance.

Secretary of State Colin Powell said Monday the Security Council would have to "make a judgment" on Iraq's cooperation after the inspectors give their report. UN Resolution 1441 on arms inspections, adopted by the Security Council on November 8, says false statements or omissions in a weapons declaration Iraq submitted last month, coupled with a failure to cooperate with inspections, would constitute a further "material breach."

The Security Council will have to assess whether there has been a "material breach" -- widely seen as a trigger for war -- and can, but is not compelled to, authorize military action.

UN arms experts combed more Iraqi sites for alleged banned weapons Tuesday. Iraq denies it possesses them.