Al-Qaida's new leader called on his followers to continue to fight the United States despite the killing of Osama bin Laden, calling America a "criminal country" that has corrupted the world.
In a video posted on militant websites Sunday, Ayman al-Zawahri also said the uprisings in Egypt and Tunisia have provided opportunities for the group to spread its message.
The 12-minute message is the third from the Egyptian-born al-Zawahri since he was named al-Qaida's new leader in June following the killing of Osama bin Laden by U.S. commandos in Pakistan.
Wearing a white robe and turban with an automatic rifle at his side, al-Zawahri said the Muslim jihad, or holy war, against America "does not halt with the death of a commander or leader" _ a clear reference to bin Laden.
"Chase America, which killed the leader of the mujahedeen and threw his body into the sea," he said. "Go after it so that history will say that God enabled his worshippers to attack a criminal country which has spread corruption in the world."
Shifting to the Middle East, al-Zawahri said the uprisings that toppled longtime autocrats in Tunisia and Egypt have presented al-Qaida an opening to spread its message.
"In Tunisia and Egypt, opportunities for preaching have been opened and only God knows until when these opportunities will last," he said. "Therefore, the Muslims and the mujahedeen should benefit and take advantage of them to reveal the truth."
Al-Qaida has repeatedly tried to forge a role for itself in the uprisings across the Arab world this year, though it played no role in their outbreak and has little in common with the mainly youth activists behind the protests. Most uprisings leaders say they seek greater freedoms, not Islamic states.
He said these countries' constitutions should be brought in line with Islamic Sharia law.
The video could not be independently verified.