Their summit in Northern Ireland will be the third in as many weeks for the two leaders, who embarked on the Iraq war without United Nations approval and in defiance of key allies France and Germany.

The two leaders met March 16 in the Azores just four days before launching the war and again on March 27 at Bush's Camp David retreat outside Washington, when Iraqi resistance was surprisingly strong.

But on Sunday US troops were advancing on Baghdad from opposite directions and planned to have Saddam Hussein's capital encircled by the end of the day, a US officer said.

Meanwhile British troops were making their most aggressive attack since the beginning of the war on the southern port of Basra, Iraq's second largest city.

Post-Saddam Iraq will be a key topic Monday for Bush and Blair, who differ over the role the United Nations should play this time around.

Washington appears to have decided to sideline the United Nations as much as possible from the process, instead favoring a provisional military administrator attached to the Pentagon until an interim administration trusted by the Iraqis can be established.

But Blair, like the French and German leaders, wants the United Nations to play a central role.

Blair said in an interview in Spanish newspaper ABC on Sunday that Britain remained deeply committed to the European Union despite divisions over the war in Iraq.

The 15-nation bloc is split between those who support the war, led by Britian and Spain, and those who staunchly oppose it, led by France and Germany.

Blair said Britain would seek fresh UN Security Council resolutions to guarantee Iraq's territorial integrity, ensure humanitarian aid quickly reached civilians in need and approve a post-war administration for Iraq.

Another burning subject to be discussed Monday which is also crucial to the post-Saddam era is the "road map" to end the Israeli-Palestinian conflict.

There are also differences over this between Washington and London.

The Bush administration would like to see new Palestinian Prime Minister Mahmud Abbas, considered a counterweight to Palestinian Authority President Yasser Arafat, formally installed before agreeing to release the road map.

The peace plan sets out five stages toward the creation of a Palestinian state by 2005. But it faces strong opposition from US ally Ariel Sharon, the hawkish Israeli prime minister.

Bush and Blair will be meeting during the week marking the fifth anniversary of the Good Friday peace agreement for Northern Ireland.

The agreement was signed in April 1988 by the British government, Catholics who want the province to join the Republic of Ireland and Protestants who want it to remain part of the United Kingdom.

Irish Prime Minister Bertie Ahern is also expected to attend, as well as Northern Ireland's political leaders, who have come up against serious difficulties implementing the Good Friday agreement.

Having staked his political future on going to war with the United States against Iraq, Blair has every right to expect some payback from Bush.

Blair and Ahern have set Thursday as their deadline for restoring devolution in the province.

"Who would have believed, in their wildest dreams, that President George W. Bush would find time to visit Northern Ireland in the middle of the war in Iraq?" the Belfast Telegraph newspaper said Saturday.

SPACE.WIRE