Turkey is to invest around $3.5 to $4 billion in Iran's South Pars gas field, an Iranian Oil Ministry official has said.

"The investment (by Turkey) will be made in phases 6 and 7 of South Pars gas field," Ibrahim Radafzoun deputy Oil Minister for planning told Fars news agency on Monday.

He added that Iran and Turkey, during the visit of Turkish Prime Minister to Iran, are to discuss Turkey's investment in the two phases of South Pars gas field as well as other mutual issues.

Recep Tayyip Erdogan and his high-ranking delegation arrived in Tehran on Monday night.

Erdogan's talks with Iranian officials will focus on, regional issues, ways to enhance bilateral ties and negotiations on economic and trade transactions.

South Pars gas field is estimated to hold about 14 trillion cubic meters of gas, or about eight percent of total world reserves.

MVZ/SC/DT