US President George W Bush and British Prime Minister Gordon Brown will present a united front against Iran's nuclear ambitions on Monday and seek to dispel media suggestions of a rift over troop levels in Iraq.
On the last day of a farewell European tour, Bush will press on with efforts to build European support for new sanctions if Iran remains defiant despite a carrot-and-stick campaign to get the Islamic Republic to suspend uranium enrichment.
Bush and Brown are expected to tread a more cautious line over the Iraq war, unpopular in both their countries and a source of deep anti-Bush sentiment in Britain.
Thousands of protesters demonstrated in central London on Sunday against Bush and the five-year-old war. Several demonstrators were injured in scuffles with police and authorities said they arrested 25 people.
Police in riot gear created a buffer to allow Bush's motorcade to reach Brown's Downing Street residence for dinner.
In a British newspaper interview published on Sunday, Bush urged Britain -- Washington's main ally over Iraq -- not to withdraw troops unless conditions on the ground allowed.
"Our answer is: there should be no definitive timetable (for a pullout)," Bush told the Observer, adding he was "appreciative" that Brown was in frequent touch about "what he and his military are thinking".
The newspaper described Bush's comments as a warning to Brown, but the White House dismissed that tone, saying there was no disagreement between the United States and Britain on Iraq.
Only about 4,200 British troops remain in Iraq, most of them stationed at a base in the south. Britain has suggested it could pull them all out by the end of 2008, but with the situation still unstable in Iraq that appears difficult.
"We've routed (al Qaeda) in Iraq," Bush told Sky News television on Sunday, presenting one of the cases why he sees the US-led military operation as vital. "That's not to say that they're not still dangerous or want to come back."
Bush has a more formal relationship with Brown than he had with the British leader's predecessor Tony Blair, Washington's staunchest supporter over the 2003 invasion of Iraq.
White House officials said Iran's defiance over its nuclear programme was likely to figure more prominently than Iraq during Monday's talks between Bush and Brown.
With much of Europe still smarting over the Iraq war, Bush has spent a lot of his week-long trip building opposition to Iran's uranium enrichment activities, which the West suspects could be employed to build nuclear bombs.
On Saturday, Iran -- which says its nuclear programme is solely for power generation -- again ruled out suspending uranium enrichment despite a package of incentives put forward by six world powers.
European Union foreign policy chief Javier Solana said at the weekend he expected a formal reply soon from Iran on the incentives package, but senior Iranian member of parliament Alaeddin Boroujerdi said Tehran was in no hurry.
Italian Prime Minister Silvio Berlusconi, French President Nicolas Sarkozy and German Chancellor Angela Merkel have all offered Bush support for efforts to prevent Iran, the world's fourth-largest oil producer, obtaining nuclear weapons.
The three UN sanctions resolutions imposed so far on Iran have been relatively limited in scope -- including targeting individuals, some firms with military links and several banks.
Flush with record oil revenues that have helped it withstand such sanctions, Iran has long ruled out ending its quest for its own uranium enrichment industry.