"This was a terrorism incident," Turkish Prime Minister Tayyip Erdogan was quoted as telling the mass-circulation newspaper Hurriyet on Thursday.
"We need to say what kind of terrorism this falls under. If we want peace in the Middle East, if we want to solve the issues, Israel first of all needs to abandon this kind of attitude. To me, this approach has cast a shadow over peace," Erdogan said.
Asked about offers by Turkey to assist in the peace process, Erdogan said: "There's nothing left to mediate. They've turned everything into a cloud of smoke... This incident has inflicted a serious wound on Middle East peace. There is nothing
resembling a 'road map' left."
Tayyip Erdogan's remarks reflect NATO member Turkey's anxiety over escalating violence in the region after Israeli missile strikes killed the wheelchair-bound cleric in Gaza City on Monday.
They also appear to be a departure from Turkey's recent overtures to mediate between Arabs and Israelis.
"This incident has inflicted a serious wound on Middle East peace. There is nothing resembling a 'road map' left"
prime minister, Turkey
Muslim Turkey has traditionally supported Palestinian aspirations to statehood but has strong military, commercial and diplomatic relations with Israel.
Erdogan, whose ruling Justice and Development Party traces its roots to a banned Islamist movement, said earlier this year Turkey had hoped to mediate between Israel and Syria, which held ultimately fruitless negotiations in the years up to 2000.
Yasin's assassination is seen as a major setback to the United States' "road map" peace plan for the Middle East.