Self-proclaimed caliph Abu Bakr al-Baghdadi made an unprecedented appearance in the Iraqi city of Mosul, which his forces helped capture last month, and ordered Muslims to obey him, according to a video posted online.
That marks a significant change for the shadowy jihadist, whose Islamic State (IS) group led a lightning offensive that overran swathes of five provinces north and west of Baghdad.
The onslaught has alarmed world leaders, displaced hundreds of thousands and piled pressure on Prime Minister Nuri al-Maliki as he seeks a third term in office following April elections.
Meanwhile, Iran yesterday said it supports Nuri al-Maliki's bid to stay on as Iraq's premier but that it is ready to back any other candidate chosen by parliament in Baghdad.
Shia-dominated Iran has said it is willing to provide Iraq advice and military assistance in the fight with Sunni insurgents who overran large chunks of Iraqi territory last month and have now declared an Islamic caliphate.
The video posted Saturday showed a portly man clad in a long black robe and turban with a long greying beard addressing worshippers at weekly prayers at Al-Nur mosque in central Mosul.
"I am the wali (leader) who presides over you, though I am not the best of you. So if you see that I am right, assist me," said the man, purportedly Baghdadi.
"If you see that I am wrong, advise me and put me on the right track, and obey me as long as I obey God."
Text superimposed on the video identified the man as "Caliph Ibrahim", the name Baghdadi took when the group on June 29 declared a "caliphate", a pan-Islamic state last seen in Ottoman times, in which the leader is both political and religious.
Last year, IS expanded into Syria, becoming a major player in the war to oust President Bashar al-Assad.
The jihadist Islamic State group has expelled more than 30,000 people from their homes in the eastern Syrian town of Shuheil, a monitoring group said yesterday.
Another 30,000 residents have been forced from their homes in the towns of Khosham and Tabia Jazeera, also in eastern Deir Ezzor province, a Britain-based NGO said.
Baghdadi has cut all ties to al-Qaeda, and his influence now rivals that of that group's global chief, Ayman al-Zawahiri.
IS is known for its brutality, executing and crucifying opponents, and photographs emerged Saturday showing its militants demolishing Sunni and Shia mosques and shrines in Mosul and surrounding Nineveh province.
Iraqi security forces wilted when faced with the initial IS-led onslaught, and while they have since performed more capably, they have struggled to retake territory from insurgents.
An assault on Saddam's hometown of Tikrit has gone on for more than a week without retaking the city, while a suicide car bomb killed 15 people Friday near the sensitive shrine city of Samarra.
Iraq has reached out for international assistance and Washington has sent military advisers, but Baghdad's request for American air strikes against the militants has been rebuffed.