President Bush prepares to hold talks with British Prime Minister Tony Blair Monday on the postwar future of Iraq. Meanwhile, coalition troops have ratcheted up the pressure on Baghdad and the country's second largest city, Basra.

With the war in Iraq now approaching its climax, President Bush is to hold talks in Belfast, Northern Ireland with British Prime Minister Blair on the postwar setup there. Meanwhile, Coalition troops are tightening the noose around Baghdad, moving to choke off access points to the capital.

After taking control of the Baghdad airport, U.S. forces began using the facility as a jumping-off point to establish a secure perimeter around the city. Speaking from the Baghdad airport, VOA correspondent Alysha Ryu said "what they're attempting to do is sort of encircle the city itself. They have cut off the major roads that are going in from the north and traffic going in and out of the north. And they're blocking that and isolating the city from the north. And they expect to do that from all corners north, west, south and east, so that they will have a secure perimeter around the city."

Fighting ranged around the capital as attackers and defenders battled with artillery, rockets, machine guns and small arms. U.S. troops probed into the city center to test the strength of the dug-in Iraqi defenders. U.S. officials say they do not know, or are not saying publicly, how strong the defenders of Baghdad are.

The total number of casualties is not known. But, speaking in Doha, Qatar, U.S. Central Command spokesman Brigadier General Vince Brooks, said coalition forces have decimated the units they have encountered around Baghdad, and taken light casualties. "What we do know is that for the forces we have encountered and focussed our efforts against, we've inflicted a considerable degree of destruction," he said. "And many of those units ceased to exist as effective combat formations."

In the south, British units fought toward the center of Basra, killing or taking prisoner an undisclosed number of defenders.

In northern Iraq, at least 17 people were killed and more than 40 wounded when, according to witnesses, a U.S. warplane mistakenly dropped a bomb on a convoy of Kurdish fighters and U.S. special operations troops. U.S. military officials say they are investigating the incident.

In his meeting with Mr. Bush on Monday, Mr. Blair is expected to push for a prominent role for the United Nations in Iraq.

The Bush administration would prefer that the United Nations have no political role in the postwar running of the country.

U.S. Deputy Defense Secretary Paul Wolfowitz said the victorious coalition would run things in postwar Iraq until power could be turned over to an Iraqi interim authority. "There are two kinds of "in-charge," I think. One kind of in-charge is, you know, waters and sewers and food and medicine; and we want to make sure those things are delivered to the Iraqi people effectively; and we'd like it as quickly as possible to be done by Iraqis," he said. "But we want to make sure it's done, and we'll do it until we're sure that they can do it."

U.S. officials say the United Nations will have a key role in the distribution of humanitarian aid, particularly food. But many U.N. and private aid workers say they are uncomfortable about working in areas that will be under military control.