Shiite militants launched rockets toward the fortified Green Zone on Friday, taking advantage of a sandstorm that gave cover from attacks by U.S. aircraft. Some rockets fell short, including one that damaged the British Broadcasting Corp. bureau. At least five other rocket explosions were heard. But U.S. authorities did not confirm any strikes inside the Green Zone, which includes the U.S. Embassy and much of the Iraq (web|news) i government. The salvos from Sadr City have come in response to a U.S.-led push into Sadr City, the Baghdad stronghold of the powerful Mahdi Army led by anti-American Shiite cleric Muqtada al-Sadr. One of the American objectives is to push militants deeper into the district and put their rockets and mortars out of range for the Green Zone.

But that also has increased the chances of the shells falling short into civilian areas. One rocket hit the roof of the BBC bureau, leaving a 3-by-5 foot hole.

"It caused structural damage but no one was injured," said Patrick Howse, the BBC bureau chief in Baghdad.

U.S. authorities plan to complete a barrier - up to 12 feet tall - in parts of Sadr City. It seeks to cut off militia movement and enable the military to exert more control over the most restive section of the district - a vast slum of about 2.5 million people.

The street battles in Sadr City began in late March after the Prime Minister Nouri al-Maliki, a Shiite, launched a crackdown against the Shiite armed groups in the southern city of Basra. He has vowed to disarm the Mahdi Army and other groups that operate outside government control.

Aid groups say at least 6,000 people have fled the homes in Sadr City to escape the fighting and seek help as food and medical supplies dwindle.

On Thursday, government envoys set strict demands for Shiite militias to end their battles, but it was unlikely that militiamen would abide by the conditions and lay down arms.

"There is no dictator in the world who did what al-Maliki is doing against his people," an al-Sadr loyalist, cleric Abdul-Hadi al-Mohammedawi, told worshippers Friday in the southern city of Kufa.

Al-Sadr last month threatened to unleash an "open war" against the U.S.-led forces but ordered the militiamen to avoid spilling Iraqi blood.

Also Friday, the U.S. military denied that the leader of al-Qaida (web|news) in Iraq, Abu Ayyub al-Masri, had been captured, saying a man with a similar name had been arrested in the northern city of Mosul.

"Neither coalition forces nor Iraqi security forces detained or killed Abu Ayyub al-Masri. This guy had a similar name," said Maj. Peggy Kageleiry, a U.S. military spokeswoman in northern Iraq.

Iraqi Defense Ministry spokesman Mohammed al-Askari said the confusion arose because the commander of Iraqi forces in the Mosul region was convinced that he had arrested al-Masri - also known as Abu Hamza al-Muhajir.

There have been false alarms in the past about al-Masri. At least twice - in 2006 and May 2007 - reports circulated that he was dead.

"Iraqi officials are dealing with a developing chain of command that often leaps to conclusions and reports success before it occurs, often under pressure from the media," said Anthony Cordesman, a security analyst for the Center for Strategic and International Studies.