Iranian President Mahmoud Ahmadinejad is expected to pay an official visit to Turkey in the upcoming weeks or months, diplomats said Sunday. Iranian Foreign Ministry spokesman, Mohammad Ali Hosseini, confirmed that Ahmadinejad's trip is on the agenda, but said no date has been set, the Anatolia news agency reported. Diplomats from the two countries are trying to agree on the program, he added. Turkish Foreign Ministry sources have also confirmed that Iranian leaders have expressed interest in meeting with new Turkish President Abdullah Gül. “It's their turn, since we made the last presidential visit,” a diplomat told the Turkish Daily News. Former President Ahmet Necdet Sezer visited Tehran in 2004. The United States opposes Turkey's establishing economic and political ties with Iran, arguing that “it could encourage Tehran to pursue its nuclear goals.” A recent agreement between Turkey and Iran on energy and natural gas sparked criticism in Washington. In November, the Turkish and Iranian energy ministers signed an accord aimed largely at building power plants and upgrading electric infrastructure. Private companies from the two countries plan to build one hydroelectric and two thermal power plants in Iran and another in Turkey. Turkey signed a preliminary agreement with Iran in July regarding construction of two natural gas pipelines through Turkish territory, one from Iran, the other from Turkmenistan. Ahmadinejad's visit will be important to both countries' efforts to boost their energy ties and explore new joint ventures, diplomats added. However there are still problems between the countries on some Turkish companies' investments in Iran. The Iranian parliament did not approve a contract with Turkcell, Turkey's leading mobile operator, to act as foreign operator in a consortium known as Irancell was originally awarded to it last year. The Iranian Transportation Ministry and the domestic Irancell partners disagreed with Turkcell over payment of a license fee and started talks with the South African company MTN for the 49 percent foreign shareholding. The court case is still pending.