Top U.N. arms inspectors said Friday they would not agree to new talks in Baghdad unless Iraq demonstrated more cooperation and met unspecified conditions. One hinted it might be necessary to meet Saddam Hussein to resolve the crisis.

Mohamed ElBaradei, the head of the U.N. nuclear agency, and chief inspector Hans Blix were invited Thursday by the Iraqis to return here for talks before their crucial Feb. 14 report to the U.N. Security Council.

In New York, Blix said he and ElBaradei would spell out conditions for a new meeting in a joint letter, which was sent to Iraq's U.N. Mission Friday night. ElBaradei, head of the International Atomic Energy Agency, said Iraq must remove major obstacles, allow inspectors to interview scientists in private and agree to the use of U-2 surveillance planes.

"We need to make sure before we go that they are ready to move forward ... on these issues," ElBaradei told reporters in Vienna, Austria.

The Baghdad meeting would give Iraq the chance to accept U.N. demands before the Feb. 14 report and possibly buy time before a threatened U.S.-led attack.

In Washington, President Bush and British Prime Minister Tony Blair dismissed Iraq's offer. Bush called the invitation a charade meant to "string the inspectors along."

Both Blix and ElBaradei said they would like to meet the country's senior leaders, perhaps including Saddam himself, if they return to Iraq, rather than the lower-ranking aides and advisers with whom they held talks last month.

"It's very important that ... we meet at the highest level of the leadership, and hear from them a clear commitment," ElBaradei said, hinting at a meeting with Saddam.

Blix said if the Iraqis suggested a meeting with Saddam, "we would describe the situation, the dangerous situation, and the main theme that we have -- cooperation in substance."

Despite Iraq's denials, the United States and Britain insist the Iraqis are hiding banned weaponry -- and have threatened to disarm them by force if necessary. The United States alone has marshaled nearly 90,000 land, sea and air forces in the Gulf region and the number is likely to double within two weeks.

In a letter to U.N. Secretary-General Kofi Annan, Iraq's foreign minister claimed the United States -- in its "feverish desire to launch war" -- might use its "technological superiority" to plant evidence that Saddam was hiding weapons of mass destruction.

Foreign Minister Naji Sabri also demanded that the United States present proof that Iraq was still holding banned weapons.

"The American administration has in the past presented more than one report that is filled with claims and accusations that lack any evidence," Sabri said, according to a ministry statement.

Secretary of State Colin Powell has pledged to present evidence about Iraq's programs before the U.N. Security Council on Feb. 5.

In their invitation to Blix and ElBaradei, Iraq offered to discuss key unresolved issues -- including private interviews with scientists and surveillance flights. It was not immediately clear, however, if new concessions had been offered.

Maj. Gen. Hossam Mohammed Amin, chief Iraqi liaison officer with the inspectors, said Friday that Iraq would not oppose flights by U-2 aircraft, as requested by the United Nations, as long as the United States and Britain stop patrols over the "no-fly" zones of southern and northern Iraq while the spy planes are in the air.

That way, he said Iraqi anti-aircraft batteries would not mistake the reconnaissance plane for American and British jets and fire on it.

The no-fly zones have been enforced by the United States and Britain since 1991 to protect Iraqi Kurds in the north and Shiite Muslims in the south from Iraq's army.

On the issue of private interviews, Amin repeated the Iraqi position that it was the scientists themselves who refused to talk to inspectors without an Iraqi official present.

"It's up to each scientist," Amin said. "It's a question of personal freedom."

The United States maintains that the government has threatened scientists with death if they agree to private interviews.

Also Friday, U.N. inspectors visited a factory about 20 miles east of Baghdad that produces fuses for missile warheads, and an agricultural supply company in Baghdad, inspectors' spokesman Hiro Ueki said in a statement. A biological team made an aerial inspection of several sites, the first such mission since the inspectors returned to Iraq. Another team went to an ammunition factory west of the capital.