The video, aired on the Qatari-based TV channel Al-Jazeera, was the first acknowledgment by al-Qaida's central leadership of the death of al-Zarqawi, who was killed in a U.S. airstrike northeast of Baghdad on June 7.

The clip showed al-Qaida's deputy leader, Ayman al-Zawahri, wearing a white robe and black turban, speaking to the camera with a picture of a smiling al-Zarqawi over his left shoulder.

Al-Zarqawi was "a soldier, a hero, an imam (Islamic cleric) and the prince of martyrs," al-Zawahri said, adding his death "has defined the struggle between the crusaders and Islam in Iraq."

Al-Zawahri, who is believed to be hiding in the mountains on the Pakistani-Afghan border, did not mention al-Zarqawi's successor, named by al-Qaida in Iraq as Abu Hamza al-Muhajer. The omission might mean the tape was recorded before the successor was chosen, or it might indicate that al-Zawahri does not endorse the new leader.

A U.S. counterterrorism official, who spoke on condition of anonymity in compliance with office policy, said authorities believe the statement is part of al-Qaida's ongoing campaign to appear relevant by showing it is aware and part of current events, such as al-Zarqawi's death. U.S. intelligence experts are reviewing the tape to determine its authenticity, but there is no reason to doubt that it is him, the official said.

In addition to repeating his customary attacks on the U.S., al-Zawahri vilified the American ambassador to Baghdad, Zalmay Khalilzad, who was born in Afghanistan. Khalilzad is "an Afghani renegade who has abandoned his religion, emigrated to America and bowed at the feet of the Zionists," al-Zawahri said.

He also attacked Iraqi Prime Minister Nouri al-Maliki, accusing him of betraying the Islamic principles of his Dawa party.

"Nouri al-Maliki, who has been selling out Islam to reach the chair of power, collaborated with the crusader invaders before and after the invasion (of Iraq)," al-Zawahri said.

Al-Zawahri and his colleagues had clearly taken pains to make the video into a homage to al-Zarqawi. Normally, al-Zawahri appears on video against a plain background with no feature other than an automatic rifle.

In Friday's tape, however, the background was an elaborate affair: a mournful mixture of blacks and dark reds, dominated by the photo of al-Zarqawi, and two dull gold columns. Whereas al-Zarqawi photographs often show a stern, if not threatening face, the picture chosen for the video showed a smiling al-Zarqawi, who was probably laughing at a joke. Just a glimpse of al-Zawahri's rifle was visible at the extreme left of the background.

During his leadership of al-Qaida's Iraqi branch, al-Zarqawi swore allegiance to

Osama bin Laden, the network's overall leader, but often had tense relations with him and al-Zawahri.

In July 2005, al-Zawahri reportedly wrote a letter to al-Zarqawi criticizing his attacks on Iraqi Shiite mosques and civilians, saying they hurt the mujahedeen's image. The al-Qaida deputy also asked al-Zarqawi for money, according to the U.S. military, which said it intercepted the message.

Al-Zarqawi apparently brushed off the criticism as he continued to attack Shiites, a strategy intended to spark a Sunni-Shiite civil war.

Al-Zawahri's reported request for money suggests that funds were flowing more readily to al-Zarqawi than to the al-Qaida command. The money probably came from supporters in Saudi Arabia and the Persian Gulf, where many of al-Zarqawi's fighters came from.

With his spectacular bomb attacks, al-Zarqawi vaulted to a hero's status among Islamic extremists across the world, stealing the spotlight from bin Laden.

In 2005 bin Laden vanished from the public eye, issuing not a single audio or videotape, but al-Zarqawi's group frequently put out messages. He portrayed himself as al-Qaida's fighter on the hottest front of "jihad" or holy war.

The tension between al-Zarqawi and al-Qaida's command appeared to have faded by early 2006, because al-Zawahri has now issued three videotapes this year in which he effusively praises al-Zarqawi.