Sheik Mohammed Sayyed Tantawi, the head of al-Azhar, which is the most prestigious school of theology in the Sunni Muslim world, said, "The kidnapping and killing of innocent people is banned and forbidden by Islam completely and those committing such acts have no Islamic values or morals."
"The Prophet Mohammed used to bury the bodies of his enemies killed in battles and wars and never mutilated them," Tantawi was quoted as saying in the "Sawt al-Azhar" newspaper, mouthpiece of the theological school.
The most revered sheik also slammed suicide-bombing attacks carried out by Palestinian Islamic militant groups against Israeli civilians.
"Whoever detonates himself against the Israeli army which is responsible for the killing of Palestinian women, children and elderly is a martyr, but targeting and killing inoffensive civilians is completely rejected and unacceptable," Tantawi said.
At least two foreigners, an American and a South Korean, were kidnapped and beheaded by Islamic extremists in Iraq who are believed to be linked to the al-Qaida network of Saudi dissident Osama bin Laden.
Notable deaths of 2014 [PHOTOS]