Tel Aviv - Israel is concerned about the future of its strategic alliance with Turkey, Israeli officials were quoted as saying Monday.

The concern follows Ankara's decision to bar Israel from participating in an October 12-24 air force exercise in the city of Konya, in Turkey's central Anatolia region.

Ankara reportedly told Israel it was worried the fighter jets it would send to participate in the exercise were used in last winter's Gaza war.

The Israeli Haaretz daily quoted a senior official at the Israeli Foreign Ministry, who spoke on condition of anonymity, as describing the ensuing crisis as "serious."

The official said the strategic ties with Turkey could be in jeopardy. He called the move unusual and said that despite earlier tensions, it was the first real violation of a tripartite agreement between Israel, the US and Turkey.

The Israeli Foreign Ministry was not immediately available for on the record comment.

Turkish Prime Minister Tayyip Erdogan has sharply and publicly criticised Israel for the three-week Gaza offensive, which killed some 1,400 Palestinians, many of them civilians. In January he walked out on Israeli President Shimon Peres at the World Economic Forum in Switzerland.

Israel considers Turkey one of its most important Muslim allies in an otherwise hostile Middle East. The two countries have enjoyed close military cooperation, but relations have become strained since Erdogan's Islamic-conservative AKP party won elections in 2002.

Another high-ranking Israeli government official told the Ma'ariv daily that Israel and other Western countries were concerned Erdogan was leading Turkey through a gradual "process of Islamization."

"Until today, Turkey has been the antithesis of Iran - a secular Muslim country with a tolerant constitution, which would like to become a member of the European Union," said the official, adding Israel was worried Erdogan was building a model that in the future could move it closer to Iran than to the countries of Europe.

Israelis for their part have also reacted angrily to Erdogan's rhetoric against their country. The Turkish tourist destination of Antalya, normally highly popular with Israelis, saw a sharp drop in bookings from Israel after the Gaza war. (dpa)