The United States and Iraq are close to a deal extending the presence of US troops beyond 2008, US Secretary of State Condoleezza Rice said.

Rice, who flew to Baghdad on an unannounced visit, said any timetable for the troop withdrawal must be "feasible".

She denied reports that the deal has already been reached but said it was close and she was hoping to iron out any remaining questions with Prime Minister Nuri Al-Maliki.

Iraqi Foreign Minister Hoshiyar Zebari also said the deal was "very close", and would include "time horizons" for US withdrawal. He repeatedly stressed that the agreement would be temporary. But neither side would confirm any specific details.

"We'll have agreement when we have agreement. So all of those stories in the newspapers about what the agreement says probably ought to be disregarded until we have an agreement," Rice told a news conference alongside Zebari.

Anti-American cleric Moqtada al-Sadr denounced the pact and said Washington was trying to twist Baghdad's arm to sign it.

The long-awaited pact will allow US forces to stay in Iraq beyond the end of this year, when a UN Security Council mandate enacted after the US-led invasion in 2003 expires.

Replacing the UN mandate with a formal US-Iraqi pact is seen as a milestone in Iraq's emergence as a sovereign state, giving Baghdad direct say over the presence of foreign troops on its soil for the first time since the fall of Saddam Hussein.

But the deal's terms are politically sensitive in both countries, with Al-Maliki determined to show that the 144,000 US troops will not stay longer than needed, and US President George W Bush keen to avoid a firm schedule for them to leave.

"We are continuing to work to make sure that any timelines that are in the agreement really do reflect what we believe can be done, what's feasible," Rice told reporters on board her plane before her arrival. "Obviously everybody is going to keep an eye on conditions on the ground."         

Iraqi officials have said they would like to see US forces cease routine patrols on Iraqi streets by the middle of next year and withdraw all combat troops by 2010 or 2011. But it is not clear how explicit such language would be in the agreement.

Iraq's chief negotiator Mohammed Al-Haj Hamoud told Reuters on Wednesday a draft of the agreement was complete and would be presented to Iraqi political leaders to approve and send to parliament. He said the draft did not include withdrawal dates.

Other issues that need to be tackled include immunity for US troops from Iraqi law and the status of prisoners held by American forces. US forces hold some 21,000 prisoners in Iraq they deem dangerous but have not charged with any crime.

Sadr denounced both Rice's visit and the pact. "Today, Condoleezza Rice, the occupation foreign secretary, arrived in Iraq to try to put pressure on the government of Iraq to accept terms dictated by the occupation to sign this ominous treaty," said a statement read out by Sadr political adviser Liwa Smeism at the cleric's office in Najaf.

A commitment to withdraw combat troops in 2010 would resemble the plan offered by US Democratic presidential candidate Barack Obama, who wants them out by mid-2010.

The Bush administration and Republican candidate John McCain say troop reductions are likely but they do not want to commit to a firm timetable. The administration began speaking in July of "time horizons" and "aspirational goals" for withdrawal. -Reuters