Tehran, July 04 (QNA) - Iran plans to invest around $70 billion (Dh257 billion) in two major offshore natural gas fields in the 2010-15 period, a senior official said in comments broadcast on Friday. Seifollah Jashnsaz, managing director of the state National Iranian Oil Company (NIOC), said Iran would invest $40 billion to complete remaining projects in the South Pars field during the fifth five-year economic plan, which runs until 2015. He did not say how Iran, which is also the world''s fifth-largest oil exporter, would finance the investments, the "Gulfnews" reported. For years it has struggled to develop its reserves and now has to contend with an international lack of credit, as well as problems specific to Iran, which is under international sanctions due to its disputed nuclear programme. Iran has increasingly turned to Asia, which in some cases still has available cash to invest and whose energy demand is expected to outpace that in the developed world. According to the "Gulfnews", another Iranian official, Hojjatollah Ghanimifard, told Reuters last Monday that Iran is in talks with Asian banks on a 1 billion euro bond to finance the development of South Pars as part of its pursuit of billions of energy sector funding. The Iranian government has agreed to the Oil Ministry''s proposal to issue such a bond to fund South Pars development, the semi-official Mehr News Agency reported yesterday. South Pars, the world''s largest reservoir of gas, is shared by Iran and Qatar. (QNA)