TEHRAN: President Abdullah Gul said Turkey backs a negotiated settlement of the Iran nuclear issue by dialogue, as he prepared to travel to Tehran on his maiden official visit, state media reported. “Turkey wants a solution for Iran's nuclear issue through negotiations and dialogue,” Gul told Iran's official news agency IRNA in what it said was an exclusive interview ahead of the scheduled trip. Gul begins a three-day visit Monday which will see him meeting top Iranian officials, including his counterpart Mahmoud Ahmadinejad. He will also visit the cities of Tabriz and Isfahan. “Iran is signatory to the Non-Proliferation Treaty and a member of the International Atomic Energy Agency. Thus, Iran's nuclear issue should be solved through negotiation and Turkey will continue to facilitate this,” Gul said. Turkey's ties with its eastern neighbor have markedly improved since Ankara's current Islamist-rooted government came to power in 2002. Last month, Turkey hosted talks between Iran and six world powers aimed at allaying Western suspicions that Tehran is secretly developing nuclear weapons, but no progress was achieved. In June, Turkey — then a non-permanent member of the UN Security Council — irked the United States when it voted against fresh sanctions the body approved against Iran, arguing that a nuclear fuel swap deal it had negotiated together with Brazil the previous month should be given a chance. Gul also places importance on the economic ties between Ankara and Tehran. “Both nations want to expand ties in all aspects,” he said. “We will discuss political, economic and cultural issues. Many Turkish investors and businessmen are travelling with me and we will hold joint economic commissions.” Iranian and Turish officials have said they want to increase trade between the two countries to $30 billion by 2015 from the present $10 billion. Turkey's improving ties with Iran, coupled with a deep crisis in its relations with long-time ally Israel, have sparked concern that NATO's sole Muslim-majority member is sliding away from the West. Ankara strongly denies any policy shift. Gul said his visit to Tehran was also in response to several trips made by his Iranian counterpart to Ankara. Meanwhile, Turkish police began arresting 162 retired and serving military officers, including former top commanders, who are on trial accused of plotting a coup in 2003 to topple Prime Minister Tayyip Erdogan's government. The trial of alleged plotters of “Sledgehammer” reflects a lingering mistrust between the traditionally secular military and a ruling party that critics say retains Islamist leanings. Erdogan denies planning to roll back the secular constitution, and his AK Party goes into an election in June as firm favourite to win a third consecutive term, but the case is among a series of domestic and foreign policy challenges. A court in Silivri, west of Istanbul, issued the arrest warrants for the defendants on Friday. In total 196 officers are on trial, around three-quarters of them still serving, and most have been in and out of detention in the past year. Not all of them attended Friday's hearing. After the court served arrest warrants, 133 were taken for health checks before being escorted on Saturday either to the town's prison or, for those on active duty, a military prison in Istanbul. The remaining 29 were expected to surrender themselves at a courthouse in Istanbul Saturday. Television images showed a coach and two mini-buses taking the defendants to prison. Concerns about political tensions are for now unlikely to unsettle investors, well-used to Turkey's turbulent political scene, so financial markets are not expected to move for now. General Cetin Dogan, former commander of the prestigious First Army, and retired commanders of the navy and air force, Admiral Ozden Ornek and General Halil Ibrahim Firtina, were among the defendants that the court ordered to be arrested. The trial, which began in December, was adjourned to March 14, and the chief judge pressed for an interim verdict to be read. Defence lawyers said their arguments were being overlooked and the arrests were unjustified. They objected to a change in judges during an earlier hearing. “There is absolutely no risk they will escape. I have been an attorney for 33 years and I can't believe what's happening on this case, this is a travesty of justice,” defence lawyer Sule Nazli Erol told CNN Turk. The “Sledgehammer” plot allegedly involved plans to bomb historic mosques and provoke conflict with Greece, as part of a plan to undermine the government and enable a military takeover. The defendants, important figures in NATO's second biggest army, deny any conspiracy and say the ‘plot' was a war game exercise at a military seminar seven years ago. If found guilty, they could face 15 to 20 years in prison.