Al-Qaida's No. 2, Ayman al-Zawahri, paid tribute to several commanders from the militant group killed in a recent U.S. strike in a new video recording posted Friday on a militant Web site.
Al-Zawahri praised the deaths of the men, calling them martyrs, and urged other Muslims to follow their lead in waging jihad, or holy war.
"So brothers, go forward and don't look back. Your path is laced with blood, and don't turn this way or that, only look up to the sky," said al-Zawahri.
Al-Qaida on Sunday confirmed the death of Abu Khabab al-Masri, who is believed to have been killed in a U.S. airstrike in Pakistan last month.
Pakistani officials have said six people were killed in that strike, in the country's lawless South Waziristan tribal region.
Al-Masri, an Egyptian militant whose real name is Midhat Mursi, had a $5 million bounty on his head from the United States. He is accused of training terrorists to use poisons and explosives and is believed to have trained the suicide bombers who killed 17 American sailors on the USS Cole in Yemen in 2000.
He is also believed to have helped run al-Qaida's Darunta training camp in eastern Afghanistan until the camp was abandoned amid the 2001 U.S. invasion of the country. There he is thought to have conducted experiments in chemical and biological weapons, testing materials on dogs.
'A group of heroes'
In the Friday video, al-Zawahri also paid tribute to three other al-Qaida commanders: Abu Mohammed Ibrahim bin Abi Farag al-Masri, Abdul-Wahab al-Masri and Abu Islam al-Masri.
He called al-Masri and the three others "a group of heroes" and warned of vengeance for their deaths.
"All these men went to their Lord to complain to him about the injustices of the Americans and the betrayal of the Pakistani government," added al-Zawahri.
The authenticity of Friday's video could not be independently confirmed but it was posted on an Islamic militant Web site where al-Qaida usually releases its statements.
The U.S. military, wary of embarrassing its Pakistani allies, has not officially confirmed it carried out the July 28 strike. Two Pakistani intelligence officials and at least one pro-Taliban militant said they believed al-Masri had died in the attack, and an American official in Washington expressed cautious optimism al-Masri was among the dead.
Both Osama bin Laden and al-Zawahri are believed to be hiding in the rugged and lawless tribal regions along the Afghan-Pakistan border. In January, al-Masri was initially reported to have been killed in a similar airstrike said to have been targeting al-Zawahri, but Pakistani officials quickly backed off claims al-Masri was killed.