It was unclear whether, or in what form, Turkish President Abdullah Gul would take Iranian President Mahmoud Ahmadinejad to task for his viciously anti-Israeli rhetoric, including a new tirade issued just hours before departing for Turkey on Thursday, Turkish sources said. Ahmadinejad arrived in Istanbul on Thursday afternoon for a two-day working visit, his first trip to Turkey since coming to power in 2005. Israeli diplomatic officials, who relayed their disappointment to Ankara last week at the invitation extended to Ahmadinejad, said Israel's Ambassador to Turkey Gabi Levy would again raise the issue with Ankara in light of Ahmadinejad's latest comments. Ahmadinejad, in an interview with Turkey's NTV and CNN Turk channels aired just before he arrived in Istanbul, said the West should not support Israel. "The life of this regime has come to an end," he said. The Islamic Republic News Agency quoted Ahmadinejad as saying that "Opposing the Zionist regime has become a global issue today. In order to continue its life, the Zionist regime needed to continue aggression and occupation but presently it is forced to erect walls around occupied lands to survive, and this means annihilation." Last week Levy relayed a message to the Turkish Foreign Ministry expressing disappointment at the invitation, and the legitimacy a visit to Turkey bestowed upon Ahmadinejad. Turkey's envoy to Israel was summoned to the Foreign Ministry in Jerusalem to hear a similar message. Turkish sources said the Iranian nuclear issue would be a major focus of Ahmadinejad's talks with Gul, and that Turkey was bound by the United Nations Security Council sanctions regime against Teheran. At the same time, Ahmadinejad was expected to sign a new gas pipeline deal with Turkey in a demonstration of the improved ties between the Islamic Republic and the NATO ally. Iran is Turkey's third-biggest natural gas supplier, and the two countries were expected to seal an agreement to build a new gas pipeline to prevent the frequent cuts in gas from Iran during wintertime. But the two sides failed to reach agreement on the construction of the pipeline, local media reported. The talks in Istanbul were still under way. Relations have improved between Iran and Turkey's Islamic-rooted leadership, which took power in 2002. Earlier Turkish governments accused Iran for decades of trying to export its radical Islamic regime to secular Turkey, which is aspiring to join the European Union. Ahmadinejad is going to Istanbul, and not Ankara, in order to skirt the issue of whether he would lay a wreath at the mausoleum of the ardently secular father of modern Turkey, Mustafa Kemal Ataturk. The mausoleum, a national shrine, is in Ankara. While the Iranian News Agency said that in addition to meeting Gul, Ahmadinejad would also hold a meeting with Turkish Prime Minister Recep Tayyip Erdogan, that meeting was in doubt because Erdogan went to Russia and Georgia on Wednesday to deal with the crisis there, and it was not clear whether he would return to Turkey in time. Washington opposes any new energy deal between Iran and Turkey on grounds that it could send a wrong message to Teheran amid the nuclear standoff. The US has also opposed plans for Turkey's investment in Iran's South Pars gas fields, and the Islamic Republic selling its gas in European markets via a US-backed pipeline through Turkey. However, Turkish officials said the deal would not violate any of the UN Security Council sanctions that have already been approved. While Turkey's military regards a nuclear Iran as a possible security threat, it has shared intelligence with Teheran as the two countries staged simultaneous attacks against a common enemy, separatist Kurdish rebels based in northern Iraq. Turkish sources said in addition to discussing Teheran's nuclear program and bilateral issues, the two leaders would also discuss the situation in Iraq. Turkish sources said that Ankara could not simply ignore Iran, since the countries are neighbors, and it was important for Ankara to have an open dialogue with the Islamic regime. AP contributed to this report.