BAGHDAD, Aug 17 –Washington’s envoy to Iraq has claimed that pulling US troops out of the country could open the door to a “major Iranian advance” that would threaten US interests in the region.

Ambassador Ryan Crocker also accused Tehran of seeking to weaken the Iraqi government so that it could “by one means or another control it”.

Crocker’s allegations clash head-on with Tehran’s public support for Iraq’s government.

Washington last week warned Iraqi Prime Minister Nouri al-Maliki of “a price to pay” for his close Iran relations as the premier visited Tehran.

Crocker and the top US general in Iraq, General David Petraeus are due to present a pivotal report to Congress in September on progress on the military and political fronts and make recommendations on the way forward.

Opinion polls suggest most Americans have turned against the four-year war and Democrats in Congress want President Bush to start pulling out US troops as soon as possible. Bush, however, has resisted such calls.

“If the leadership wants to go a different way, I have an obligation to talk a little bit about what the consequences of pulling in a different direction would be,” Crocker told Reuters in an interview.

“One area of clear concern is Iran. The Iranians aren’t going anywhere. I have significant concerns that a coalition withdrawal would lead to a major Iranian advance. And we need to consider what the consequences of that would be.”

Crocker has met his Iranian counterpart in Baghdad three times to discuss the issues of Iraq security.

“Based on what I see on the ground, I think they are seeking a state that they can, by one means or another, control, weakened to the point that Tehran can set its agenda,” he claimed.

Crocker alleged that Tehran was seeking “greater influence, greater pressure on the government”.

Bush sent 30,000 extra troops to Iraq earlier this year.

While Petraeus will look at the success of the US military build-up, Crocker has the arguably more difficult task of reporting on the almost negligible political progress that has been made towards reconciling Iraq’s warring groups.

With the Bush administration often accused of not giving much thought about what do in Iraq after it invaded in 2003 to topple Saddam Hussein, Crocker said he was anxious to spell out the consequences of pulling out US troops.

“If we decide that we tried, we’re tired, we want to bring the troops home, then what? The movie does not stop the day that coalition forces leave Iraq. It keeps on running. We need to consider what reels two, three, four and five might look like.”

Crocker said he was in daily contact with Petraeus but had not yet begun to draft his report, which is due to be presented on Sept. 15 and is seen by many as a watershed moment in the war that could trigger a change in U.S. policy.

“I have come to find here in Iraq that a month is a long span of time,” he said.

He said the US military buildup and new alliances formed with Sunni Arab sheikhs that have pacified volatile Anbar province had brought Maliki’s government to a cross-roads.

“This is the best chance they have had since the beginning of 2006. It is an opportunity to really start turning things around in this country. But they are going to have to move in a decisive, considered and comprehensive way.”

Iraq’s leaders have been meeting this week to try to find common ground and break the political logjam that has paralyzed decision-making.