The new US ambassador to Iraq, Ryan Crocker, used his first press conference since arriving in Baghdad last month to insist that the wall was not intended to segregate the city's warring Sunni and Shiite communities.

"I think it's important ... that one not lose sight of the threat that is motivating some of the decisions that have been made," Crocker said.

"The intention in Adhamiyah is clearly not to segregate communities nor to engage in a form of political or social engineering," he continued.

"It's to try to identify where the faultlines are, where avenues of attack lie and to set up the barriers literally to prevent those attacks."

The spokesman for the Iraqi forces engaged alongside US troops in enforcing the Baghdad security plan, Brigadier General Qassim Atta, said that many other districts already had or would have some form of barrier.

Some of these might be walls, but others ditches, sand-bags or fences, he said, and accused the news media of inflating the size of the five metre (16 feet) tall concrete barricade that US troops are erecting around Adhamiyah.

"In fact the Adhamiyah security barrier has been exaggerated by the media, and we anticipated there would be some reactions by weak-minded people," he said, referring to criticism of the plan by many Iraqi politicians.

Atta said Iraqi units involved in planning and building walls are under Maliki's command and implied the prime minister had reacted to false reports, saying: "He said he would not accept a 12 metre high security barrier."

Asked about the wall on Sunday, Maliki said: "I am opposed to the building of the wall and its construction is going to stop."