DUBAI (Reuters) - Al Qaeda leader Ayman al-Zawahri has urged Muslims to avenge the burning of copies of the Koran on a U.S. base in Afghanistan earlier this year, dismissing apologies for the incident as a "ridiculous farce".
Zawahri, who took up the reins of al Qaeda after the killing of Osama bin Laden in Pakistan just over a year ago, said Muslims should kill those responsible for desecrating their holy book and Afghan lands.
"Once again, the crusaders burned the holy Koran, in Kabul," said Zawahri in the short audio message posted on Islamist Internet forums.
"After each of their numerous crimes they pretend to be sorry and claim they will investigate what happened. That is the ridiculous farce Obama and his defense minister repeated this time as well."
The authenticity of the recording, which did not have an exact date, could not immediately be verified, but the speaker sounded like Zawahri in previous messages.
"Kill those aggressors who occupied your country, stole your wealth, violated your honor and attacked your Koran and your prophet, peace be upon him," Zawahri added.
President Barack Obama apologized for the burning of the Koran in February, which sparked violent protests and frayed already tense U.S.-Afghan ties.
U.S. Defense Secretary Leon Panetta also expressed regret for the "inappropriate treatment" of Islam's holy book.
In February, a tape of Zawahri was released in which he said U.S. decisions to cut its defense budget and engage with the Afghan Taliban were signals of a decline in Washington's power.
(Reporting by Isabel Coles; Editing by Myra MacDonald)