Influential Shi'ite cleric Moqtada al-Sadr says his supporters will resume their fight against U.S. forces in Iraq if they stay beyond a deadline to withdraw at the end of the year.
A spokesman read out a statement from the cleric Saturday to hundreds of thousands of his followers gathered in Baghdad.
Sadr's Mahdi Army militia battled U.S. forces for years following the U.S. invasion of Iraq, until declaring a cease-fire in 2008.
His announcement comes after U.S. Defense Secretary Robert Gates told U.S. troops in Iraq that the United States would be willing to maintain a military presence past the end of the year if the Iraqi government requests it.
Currently, about 47,000 U.S. soldiers remain in the country to train and advise Iraqi forces. Iraqi Prime Minister Nouri al-Maliki recently said his army is increasingly capable of establishing security on its own.
Some information for this report was provided by AP, AFP and Reuters.