|Moqtada al-Sadr said attacks on US troops would resume and would be severe if the forces did not leave Iraq [EPA]
Moqtada al-Sadr, Iraq's Shia leader, has ordered his followers not to attack US troops before the completion of their pullout from the country, which is scheduled by the end of the year.
But Sadr, whose political movement is a key ally to prime minister Nuri al-Maliki's fragile coalition of Shias, Sunnis and Kurds, warned that military operations would resume and would be severe if US forces did not depart on time.
He said Iraq could regain its independence only when US forces had left the country.
"Because of my eagerness to accomplish the independence of Iraq and have the invader forces withdraw from our holy land, it has become imperative for me to stop military operations ... until the invader forces complete their withdrawal," Sadr said in a statement read out by Salah al-Ubaidi, his spokesman.
"If the pullout is completed and there is no longer a single US soldier on our territory, the military operations will end definitively but if that is not the case and Iraq remains in a state of dependency, they will resume with greater vigour," Sadr said.
Last July, Major General Jeffrey Buchanan, a spokesman for US troops in Iraq, accused three Shia armed groups of being behind attacks on US troops.
He named them as the Promised Day Brigades, formed by Sadr in November 2008, and Kataeb Hezbollah and Assaib Ahl al-Haq, two splinter groups which broke away from Sadr's former Mehdi Army, which fought US-led forces from 2004 to 2007.
The new US army chief warned on Thursday against leaving too large a force in Iraq after a year-end deadline, saying too many soldiers on the ground could feed the perception of an American "occupation".
General Ray Odierno commanded US forces in Iraq until last year and was one of the senior officers who spearheaded the troop "surge" in 2007.
The military believes the move turned the tide in the war and reduced sectarian violence, mainly between Shia and Sunnis.
He spoke amid a debate in Washington over the scale of a possible future US military mission in Iraq and after Leon Panetta , the defence secretary, endorsed a tentative plan for a force of 3,000-4,000 troops.
Some US legislators have criticised that number of soldiers and say senior officers favour a larger force of at least 10,000, which would include a unit deployed in northern Iraq to defuse Arab-Kurdish tensions.
But Odierno told reporters the United States had to carefully balance how many troops were needed to assist Iraqi forces while scaling back its forces' profile in a country where anti-US sentiment still runs high.
"I will say when I was leaving Iraq a year ago, I always felt we had to be careful about leaving too many people in Iraq," said Odierno, who took over as army chief of staff on Wednesday.
"The larger the force that we leave behind ...[the more] comments of 'occupation force' remain," he added.