Al Qaeda's second-in-command vowed vengeance against the United States for the death of Abu Musab al-Zarqawi, the leader of al Qaeda in Iraq killed in a U.S. air strike two weeks ago.

Al Qaeda's second-in-command Ayman al-Zawahri speaks in this file video footage released April 29, 2006. In a separate video tape aired by al Jazeera television on June 23, 2006, Al-Zawahri vowed vengeance against the United States for the death of Abu Musab Al-Zarqawi, al Qaeda's leader in Iraq killed in a U.S. air strike two weeks ago. [Reuters]

"Yes (George W.) Bush, there isn't a single person who'll be killed that we won't get vengeance for, God willing," Ayman al-Zawahri said in comments addressed to the U.S. president on a videotape aired by al Jazeera television late on Friday.

"Do you remember, Bush, the mujahid Osama bin Laden's vow that America will not dream of security until we experience it in Palestine? ... So try uselessly to dream of peace," said Zawahri, bespectacled and wearing a black turban.

Zawahri hailed Zarqawi as a martyr and attacked Iraqi Prime Minister Nuri al-Maliki, saying, "he traded the name of Islam to get to the seat of power." He also blasted U.S. Ambassador to Iraq Zalmay Khalilzad, calling him an "Afghan infidel."

Zawahri addressed the American public, saying Bush was lying when he says the United States would "win" by killing Osama bin Laden, Taliban chief Mullah Omar and other leading Qaeda and Taliban figures.

"He (Bush) is hiding from you the real disaster you're facing," he said, against a backdrop of a picture of Zarqawi and a banner stating: "Zarqawi, the Muslim nation's martyr and the prince of martyrs.

"You're not facing figures or organizations but you're facing the Muslim nation which is flowing with the spirit of jihad."

A U.S. counterterrorism official said there was no reason to doubt the authenticity of the videotape, which he said was the eighth Zawahri had released since January 2006.

Speaking on condition of anonymity, he described Zawahri's direct addresses to Bush as "jihadist bravado."

"It's part of their ongoing propaganda campaign to appear relevant by commenting on current topics," the official said.

Zawahri attacked religious scholars in Iraq as "those who subscribe falsely to Islam."

He also lambasted Turkey for being a secular country and one which dismissed Islamic law, welcomed U.S. bases and recognized Israel.

In a three-minute Internet video posted on Thursday, Zawahri urged Afghans to fight foreign troops in their country whom he said had a history of denigrating Islam.

Abu Hamza al-Muhajir, named as the new leader of al Qaeda in Iraq, has also vowed to avenge the killing of his predecessor.