Updated

U.N. weapons inspectors climbed aboard a plane and pulled out of Iraq on Tuesday after President Bush issued a final ultimatum for Saddam Hussein to step down or face war.

U.N. Secretary-General Kofi Annan on Monday ordered all U.N. inspectors and support staff, humanitarian workers and U.N. observers along the Iraq-Kuwait border to evacuate Iraq after U.S. threats to launch war.

After failing to secure U.N. authorization to use force to disarm Iraq, Bush gave Saddam 48 hours to step down or face war in a speech Monday night.

A plane carrying the inspectors took off Tuesday morning from Saddam International Airport and later landed in Laranca, Cyprus, where the inspectors have a base.

U.N. officials said about 150 inspectors, support staff, humanitarian workers and observers would be evacuated.

"We left Iraq with a sense of sadness," U.N. spokesman Hiro Ueki said in Cyprus. "We have done our job to the extent that we could. All the staff did this the best possible way, both objectively and professionally."

Ueki said 56 inspectors as well as support staff were on the first flight. He said that two more flights were planned and that the exodus would be complete by the end of the day.

U.N. observers started to leave Kuwait on Tuesday as well. The observers have patrolled the desert border area between Kuwait and Iraq since the end of the 1991 Gulf War.

U.N. weapons inspectors arrived in Baghdad for the first time in four years on Nov. 27, 2002, and resumed inspections two days later. During four months of inspections, arms experts traveled the length of the country hunting for banned weapons of mass destruction.

Chief U.N. weapons inspector Hans Blix has said that during those inspections, inspectors never found any "smoking gun."

Saddam made a last-minute bid to avert war, admitting that Iraq had once possessed weapons of mass destruction to defend itself from Iran and Israel -- but insisting that it no longer has them.

"We are not weapons collectors," the official Iraqi News Agency quoted him as saying.

"When Saddam Hussein says he has no weapons of mass destruction, he means what he says," Saddam said.

Bush's speech Monday night set the countdown clock for war. "The tyrant will soon be gone," Bush said, either by Saddam's own choice to leave or by force. Saddam and his sons must leave Iraq within 48 hours, Bush said.

After the speech, the Iraqi ambassador to the United Nations dismissed the threat.

"The Iraqi side refused to accept what has been said by Bush, and this will be really the very bad solution for the whole region, for Iraq, for the United States ... and for the humanity, Ambassador Mohammed Al-Douri said.

"This will destabilize not only the region but other parts of the world. So I think this would be a mistake, a grave mistake from the part of the American administration to launch this war against my country."

Iraqi Information Minister Mohammed Saeed al-Sahhaf said Saddam wouldn't leave. "He will stay in place like a solid rock," he told the Al-Jazeera TV network.

Baghdad residents prepared for the worst, flooding markets to stock up on food, lining up for gas and bread and taping their windows for fear of flying glass from U.S. bombs.

Diplomats from Germany, the Czech Republic, India, China, Bahrain and Britain, were already leaving Iraq as well as neighboring Kuwait amid fears that Baghdad could retaliate against any U.S.-led war.

The United States had already ordered all government dependents and nonessential staff out of Kuwait, Syria, Israel, the West Bank and Gaza Strip; on Monday, it suggested that Americans in Lebanon should consider leaving.

Foreign journalists, including crews from ABC, NBC and China's Xinhua news agency, were heading out of Baghdad. The number of foreign journalists in the Iraqi capital has dropped from 450 to 300 in the last week, according to the Information Ministry.

In Kurdish-controlled northern Iraq, residents streamed out of the city of Chamchamal, a mile from Iraqi forces, heading deeper into the relative safety of Kurdish territory protected by U.S.-British air patrols. Cars, buses, tractors and pickup trucks were laden with rugs, suitcases and other belongings.

More than 250,000 U.S. and British troops are in the Persian Gulf, ready to strike.

U.S. military officers in the Kuwaiti desert issued troops ammunition and showed them photographs of Iraqi soldiers so they could differentiate the different units and ranks. British Royal Marines gathered around portable radios to wait for any news on how soon they may go to war.