Al-Azhar, the top Sunni Muslim authority, on Monday denounced as "barbaric" the burning of the Koran on a US base in Afghanistan and called for US troops to leave the country immediately.
"Al-Azhar does not accept any tampering with the Koran... or that it be attacked in a barbaric way," the grand imam of the Cairo-based Al-Azhar, Sheikh Ahmed al-Tayyeb, said in a statement.
"It is a violation of the red lines which no Muslim can accept," he added.
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Tayyeb described the burning of the Koran at the US airbase at Bagram near Kabul as "aggression against the sacred values of human heritage."
"The military force (behind the) aggression should immediately leave Afghanistan," he said.
"The immediate departure from Afghanistan of these forces is the only solution to this crisis, in order for the Afghan people to decide by themselves their destiny," he added.
Deadly protests have erupted in Afghanistan following the burning of Korans by US soldiers.
US President Barack Obama has apologised for the Koran burning while his Afghan counterpart Hamid Karzai has appealed for calm.