YALTA, Ukraine: A film mocking Islam that sparked protests across the Islamic world is a provocation against Muslims but should not be used as a pretext for violence, Turkish Prime Minister Recep Tayyip Erdogan said Friday.

"This is a strong provocation against our way of life," Erdogan said in a speech at a conference in the Ukrainian Black Sea resort of Yalta.

"Insulting the prophet cannot be justified as freedom of expression. Religion and the prophet are sacred values and are untouchable."

But he added: "It cannot be a reason for innocent people to be attacked or harmed.

"This is justified by nothing and above all not by Islam. No-one can, in the name of Islam, carry out actions of the kind that happened in Libya with the attack on the U.S. mission" in Benghazi, he said.

US and Libyan officials are probing an attack on the U.S. consulate in Libya that killed the ambassador and three other U.S. officials, amid growing speculation it was the work of militants rather than demonstrators.

Erdogan said: "Legal and peaceful protest by Muslims is a useful and correct thing. But a protest cannot envisage any kind of violence or terrorism."

The amateurish film denigrating the Prophet Mohammed has been allegedly linked to evangelical and Coptic Christians in the United States.