Oil and Natural Gas Corp (ONGC) and its partner Hinduja Group may sign a multi-billion dollar deal next month for developing oil and gas fields in Iran.The ONGC-Hinduja combine would meet Iranian the authorities around mid-April to finalise "participating agreement" for the development of Phase-12 of the giant South Pars gas field and South Azadegan oilfield, ONGC Chairman and Managing Director R S Sharma told reporters here today.The consortia was in Tehran earlier this month to do technical due diligence for the two fields but ended up being shown old data for the Phase-12 and no data of South Azadegan."The next meeting is scheduled tentatively around mid-April... We hope to sign participating agreement (for the two fields) then," Sharma said.The development of the two fields are part of the $20 billion investment ONGC and Hindujas have planned together.Hindujas, together with state-run ONGC's overseas arm ONGC Videsh, are to invest $8 billion in developing the onshore South Azadegan oilfield and Phase-12 of the offshore South Pars gas field.The two firms would court Switzerland-registered Naftiran Intertrade Co (NICO), a unit of National Iranian Oil Co for the deal, he said.NICO has been offered a stake in the 15 million tons oil refinery, one million tons petrochemical plant and 7.5 million tons LNG receipt facility planned by Hinduja-ONGC at an investment of over $10 billion at either Kakinada in Andhra Pradesh or Mangalore in Karnataka.Petropars, the subsidiary of NICO that has been awarded development rights for South Pars Phase-12, and PetroIran, another subsidiary of NICO owns 90% development rights of Azadegan oilfield.