"No, no Chalabi," about 150 protesters chanted as US troops tried to clear a lane of at least three vehicles near Haboby Square, a gathering point with markets and a bus station close by.

The US soldiers were on the verge of using tear gas as the protesters grew increasingly agitated and closed around the vehicles to prevent them from leaving, but the troops finally pulled back as the tension eased.

"He (Chalabi) knows nothing about here," one of the protesters, Muhsin Fiadh, told AFP.

"He came with America to control our country. We don't know Chalabi. We want someone who knows us."

Chalabi is a wealthy Shiite Muslim who lived in exile during Saddam's reign and heads the umbrella Iraqi National Congress.

He recently returned to Iraq and set up on the outskirts of Nasiriyah, drawing a high profile because of strong backing from sections of the US government to be the nation's next president.

Muhsin said the protesters wanted to be governed by the premier Shiite school of Islamic leaders in Najaf, the Hawza.

The protest echoed a much larger rally earlier in the day through Nasiriyah which was attended by up to 20,000 people, journalists estimated.

However other people in Nasiriyah said the political process was being hijacked by Islamic groups who did not really want democracy, with some agitators coming from neighbouring countries.

"There are strangers who come from outside the country and want to make violence," Amer Al Obidi, who is the president of a small political movement calling itself the Liberal Democratic Party, said just metres from the anti-Chalabi protest.

"They want to blacken the name of Mr Chalabi."

The rallies appeared to have been ignited by a US-sponsored meeting of Iraqi opposition groups at a secured airbase less than 10 kilometres (six miles) from Nasiriyah.

Chalabi was to attend the historic meeting but at the last minute decided to send a representative instead.

Many Iraqis are wary of what they see as a US bid to control the nation and its vast oil resources, while Iraq's neighbours -- particularly close US ally Turkey -- fear the nation will split apart along ethnic or factional lines.

Nasiriyah was severely damaged during intense fighting during the initial stages of the US-led war that toppled Saddam Hussein.

The population is growing increasingly restless because they have been without water and electricity for nearly a month.

There is a small US military presence in the city guarding key bridges and other strategic sites.

SPACE.WIRE