Usama bin Laden's (search) right-hand man claimed mujahedeen, or holy fighters, have taken control of much of Afghanistan and driven U.S. forces into the "trenches."
Southern and eastern Afghanistan have been wracked by the fiercest resistance to U.S. military forces and there have been frequent attacks on Afghan election workers preparing for an Oct. 9 presidential vote.
However, no Afghan provincial government is considered in jeopardy of falling and Afghan and U.S. forces have largely controlled the country.
The tape was released two days before the third anniversary of the Sept. 11 terror attacks staged by Al Qaeda.
Wearing a white turban, the Egyptian surgeon said "southern and eastern Afghanistan have completely become an open field for the mujahedeen." An assault rifle was leaning on the wall behind him.
"The Americans are huddled in their trenches, refusing to come out to confront the holy warriors despite the holy warriors' provoking them by shelling, shooting and cutting the routes around them, and their defense concentrates on strikes from the air which wastes America's money in kicking up dust," al-Zawahri said in excerpts of the tape aired by the Qatar-based station.
Al-Zawahri also said the peacekeeping force still in Afghanistan has been "burnt by the shells of the holy warriors and expect martyrdom operations all the time, with God's help."
The last statement purported to have been made by al-Zawahri surfaced June 11, when an audiotape believed to be that of the Al Qaeda No. 2 was broadcast by Al-Arabiya TV, on which the speaker said a U.S. plan for reform in the Middle East was really a bid to replace Arab leaders.
Al-Jazeera said it had received the latest al-Zawahri tape exclusively, but it was not immediately clear how or when it received it.
Bin Laden and al-Zawahri are believed hiding along the rugged Afghan-Pakistan border.
They also issued video and audiotapes around last year's anniversary, including one on Sept. 10, 2003, that showed the two men walking through rocky terrain. Two taped messages accompanied that video, including one in which bin Laden's praised the "great damage to the enemy" done on Sept. 11.
President Hamid Karzai (search) has said recently that he considers infighting among pro-government warlords a larger threat to the nation's stability than that posed by the remnants of the Taliban regime.
Hd News' Bret Baier and The Associated Press contributed to this report.