Oil and Natural Gas Corp (ONGC) had 20 per cent stake and GAIL 10 per cent stake in A-1 and A-3 offshore blocks, where independently certified reserves are put at 4.53 trillion cubic feet.
South Korean trading company Daewoo International Corp was the operator with 60 per cent stake and Korean Gas Corp (KOGAS) had the remaining 10 per cent.
However, as per the production sharing contract for the field, Myanmar Oil and Gas Enterprise (MOGE) had a 'step-in' right to take 15 per cent stake once discoveries are made.
"We have entered the development phase and MOGE has exercised its 'step-in' right. Subsequent to that, the stake of ONGC Videsh Ltd (the overseas arm of ONGC) has been cut proportionately to 17 per cent and that of GAIL to 8.5 per cent," an official in the consortium said on the sidelines of the World Petroleum Congress in Madrid.
Daewoo now holds 51 per cent and KOGAS 8.5 per cent.
The official said Daewoo last week signed a preliminary deal with Chinese state-run company PetroChina to sell natural gas to be produced at the field by 2013. The deal defines the terms of production, transportation and sale of natural gas to be produced in the A-1 and A-3 gas blocks.
Under the deal, gas will be priced at USD 4.279 per million British thermal units at the wellhead and will move in step with international oil prices every three months.
The price offered by PetroChina is lower than USD 4.41 per mmBtu price offered by GAIL to piping the gas to India but the military-ruled Myanmar decided to sell gas to China.