Ahmadinejad was concluding a two-day "working visit" to Istanbul on Friday without showing any leniency that his Turkish hosts had hoped to secure during talks with President Abdullah Gul and other top leaders eager to play a constructive mediating role in defusing the Iranian nuclear crisis with the West.

Officials said that Gul met for a second time with Ahmadinejad on Friday, after a 90-minute, one-on-one meeting with the Iranian leader on Thursday night failed to make a breakthrough.

Reports said that Gul advised the Iranian leader to accept a recent incentives deal by the five permanent members of the U.N. Security Council and Germany asking Iran to stop uranium enrichment or face a new set of tougher international sanctions.

Sources said the Turkish president told his Iranian counterpart not to underestimate the U.S. warnings by continuing to insist that the American presence in Iraq and the region was becoming weak or that America would not dare launch a military attack on Iran.

In a joint news conference after their first meeting on Thursday night, Gul said his country would do all it can to ensure a successful diplomatic solution to the nuclear standoff, while the Iranian president said there should be "more focus" on the common elements between the Western and Iranian proposals in this regard.

Ankara fears a possible U.S. or Israeli military strike against Iran – an important trade partner for Turkey where bilateral trade is expected to reach $10 billion this year – would throw the region into turbulence.

Nevertheless, Gul's reported advice appeared to have fallen on deaf ears, as Ahmadinejad politely insisted that while he appreciated Turkey's concern, Iran was handling its nuclear crisis through its negotiations with the West.

Iran, under three sets of international sanctions, refuses to stop uranium enrichment, which it says is essential to meet growing energy needs in the country. It denies as mistaken Western fears that it plans to build atomic weapons, saying its program was entirely peaceful.

Ahmadinejad, on his first visit to Turkey since he was elected president in 2005, reportedly told Turkish leaders that he did not want the nuclear issue to get in the way of boosting their bilateral relations and cooperation.

Ankara had ignored criticism by its U.S. and Israeli allies to receive the defiant Iranian leader, who has called for the elimination of Israel and predicted the collapse of the United States.

Turkey justified Ahmadinejad's visit as necessary due to the failure to resolve the nuclear standoff and hoped that its growing mediating roles in the region, such as restoring the Israeli-Syrian peace negotiations after an eight-year freeze and brokering their indirect talks, would spill over to Iran.

Turkish critics who opposed the Iranian president's visit accused the government of using the nuclear issue as an excuse to boost its economic ties with Tehran.

The country's powerful secular establishment has opposed Ahmadinejad's visit, citing he would try to export the Islamic revolution to the country.

Interestingly, the government decided to receive him in Istanbul rather than Ankara, and did not describe it as a "state visit," where it is customary for heads of state to lay a wreath on the mausoleum of Kemal Ataturk, the father of secular modern Turkey following the collapse of the Islamic Ottoman Empire at the beginning of the 20th century.

However, as a devout Muslim, Ahmadinejad sent a political message to the secular establishment by conducting his Friday prayers in an Istanbul mosque with local worshippers. And he raised eyebrows in a news conference later when he spoke about how the fall of the Ottoman Empire had brought many problems to the Middle East.

Turkish analysts expected criticism to rise even on the bilateral front and the government's failure to secure natural gas and electricity deals with Iran, saying that Ahmadinejad's visit may not have been worth defending at home or with its Western allies, after all.

Ankara had expected that Ahmadinejad's talks with Gul would lead to concluding an accord for a new pipeline to carry natural gas to European markets, to the dismay of Washington as it seeks to impose new U.N. sanctions on Tehran.

The Iranian leader told reporters that "we have reached important agreements on natural gas and electricity, and we will complete them as soon as possible." He added that talks were still being held, while Turkish press reports said the bargaining was stuck over Iran's pricing.

Iran, on the other hand, grabbed a security cooperation agreement and several memorandums of understanding related to trade, culture and transport to boost bilateral ties.

Commentators said Ahmadinejad's visit seemed to have met only Iranian demands and may have left the Turkish government looking as if it had merely provided a platform for the Iranian president in a NATO member country to show that U.S.-led efforts to isolate the Islamic republic are doomed to fail.

Ahmadinejad's broad smile as he was received by Prime Minister Recep Tayyip Erdogan on Thursday spoke volumes, observers said. After all, he spent two "working" days in a secular country regarded as one of the U.S.' closest allies, an Israeli military ally, and one that has taken strides in its bid to join the European Union. And all the while, the Iranian president stuck to his guns.