IBlix, head of the U.N. commission responsible for searching for chemical and biological weapons and missiles, arrived in the Iraqi capital on Monday with a 30-strong team of inspectors. 

Mohamed ElBaradei, director of the International Atomic Energy Agency and chief nuclear weapons inspector, is also working alongside Blix. 

"The situation is tense at the moment, but there is a new 
opportunity and we are here to provide inspection which is 
credible... We hope we can all take that opportunity together." 

He added: "There is a new opportunity and we hope that opportunity will be well-utilised so that we can get out of sanctions. And in the long term, we will have a zone free 

The mission begins almost four years after the previous team was removed by the U.N. just before the United States accused Iraq of non-cooperation and launched four days of air strikes called Operation Desert Fox. 

The small team of inspectors is expected to begin work on November 27, with the teams reaching full strength by the end of the year. 

They are scheduled to report to the U.N. Security Council for the first time by January 27, two months after the inspections begin. 

But the first test of Iraq's will to cooperate comes on December 8, when the Iraqis are to hand over a declaration of their entire programme of weapons of mass destruction. 

Blix then has 60 days to report back to the U.N. Security Council with his findings. Iraq has denied possessing or manufacturing any weapons of mass destruction. 

"We hope, trust and expect that they will report whatever may remain from their programme and also a great deal of things from the sector they claim are for peaceful purposes in nuclear, biology or chemistry," Blix said. 

"We think they should look into their stores and their stock and give the world a correct declaration," he said. 

The inspectors are working with the backing of a U.N. Security Council resolution which gives them the right to go anywhere at anytime and warns Iraq it will face "serious consequences" if it fails to cooperate. 

Blix said: "It certainly is a challenge to try to find underground installations. We do expect to get tips from the member states, and we also have modern equipment that is superior to what we've had in the past." 

The C-130 aircraft carrying the inspectors touched down shortly before 1:30 p.m. (5:30 a.m. ET), about two hours after departing Larnaca, Cyprus – from where logistical support for the mission will be provided. 

ElBaradei said: "We do not take 'no' for an answer. We have to verify that a 'no' is actually a 'no'." 

Blix also reiterated statements made on Saturday that he would not tolerate spying by members of the inspection teams -- an allegation made by the Iraqis and by former inspector Scott Ritter about previous inspection missions, but denied by Western nations. 

After Iraq's 1990 invasion of Kuwait, the Security Council imposed economic sanctions that cannot be lifted until U.N. weapons inspectors verify that Iraq is free of weapons of mass destruction and the missiles that could deliver them. 

The inspectors left Baghdad in December 1998, on the eve of U.S.-British airstrikes, amid allegations that Iraq was not cooperating with the teams and Iraqi accusations that some of the inspectors were spies.