BAGHDAD, Iraq (CNN) -- Iraqi Shiite cleric Muqtada al-Sadr has extended for six months the cease-fire he imposed last summer on his Mehdi Army militia, al-Sadr's office in Baghdad said Friday.
A Baghdad street is reflected in the glass over a poster of powerful Iraqi Shiite cleric Muqtada al-Sadr.
The official said a letter was distributed to all al-Sadr offices announcing the extension of the suspension, credited by the U.S. military with helping reduce the sectarian violence that has engulfed Baghdad and other hot spots across the country.
The cease-fire is "an important commitment that can broadly contribute to further improvements in security for all Iraqi citizens," said a U.S. military statement delivered by Navy Cmdr. Scott Rye.
"It will also foster a better opportunity for national reconciliation and allow the coalition and Iraqi security forces to focus more intensively on al Qaeda terrorists," the statement said, referring to the predominantly Sunni militant group al Qaeda in Iraq.
The Iraqi government on Friday welcomed the decision.
"This step will contribute to the establishment of security and support of the national unity, and push forward the efforts of rebuilding and construction," Iraqi Prime Minister Nuri al-Maliki said in a statement.
He called the Sadrists a "cornerstone in the political process."
The cease-fire was announced in late August after pitched battles in Karbala and other cities between the militia and fighters aligned with its Shiite rival, the Islamic Supreme Council of Iraq.
There were questions as to whether al-Sadr would continue his cease-fire.
There had been some anger in the Shiite community over operations by the U.S. and Iraqi militaries, which have been going after Shiite militants who have ignored the call the stand down.
Rogue followers of al-Sadr are thought to be among the recalcitrant militants.
"Those who honor al-Sadr's pledge will be treated with respect and restraint," the U.S. military said. "Those who dishonor the Sadr pledge are regrettably tarnishing both the name and the honor of the movement."
• Fifteen bodies were discovered Thursday in a mass grave about 10 miles north of Baquba, the capital of Diyala province, an Iraqi army official said.
• UNICEF on Friday reported a measles outbreak centered in Anbar province. The agency has confirmed 27 cases of the disease, which can cause brain damage, blindness and immune system deficiencies. A five-day emergency immunization campaign in the Anbar cities of Hit and Ramadi seeks to reach every child between ages 1 and 5.
• A U.S. Marine was killed in action Thursday in Anbar province, west of Baghdad, the U.S. military said Friday. An Army soldier also died, of non-combat causes, the military said. Since the start of the war, 3,970 U.S. troops have died in Iraq, including 26 this month.
• A car rigged with explosives blew up in Tikrit in northern Iraq on Friday, killing two police officers and wounding six others, police said. E-mail to a friend
CNN's Erin McLaughlin contributed to this report.