TEHRAN, Oct. 27 (Xinhua) -- Turkey is to invest around 3.5 to 4 billion U.S. dollars in Iran's southern gas field, the semi-official Fars news agency reported Tuesday, quoting an official from Iran's Oil Ministry.

    "The investment will be made in phases 6 and 7 of South Pars gas field," Ibrahim Radafzoun, Iran's deputy oil minister for planning, was quoted as saying.

    Iran is to discuss Turkey's investment in the two phases of South Pars gas fields as well as other mutual issues with visiting Turkish Prime Minister Recep Tayyip Erdogan and his high-ranking delegation, the official said.

    Erdogan arrived in Tehran on Monday night. He is scheduled to meet with Iran's supreme leader Ayatollah Seyyed Ali Khamenei, President Mahmoud Ahmadinejad, Parliament Speaker Ali Larijani andForeign Minister Manouchehr Mottaki.

    South Pars gas field is estimated to hold about 14 trillion cubic meters of natural gas, or 8 percent of total world reserves, according to the report.