The government had last month hiked domestic natural gas prices by 33 percent to USD 5.61 per million British thermal unit. In case of RIL's main gas field in KG-D6 block, it, however, ordered buyers to pay the firm old rate of USD 4.2 and deposit the balance USD 1.41 in the gas pool account.

The incremental USD 1.41 would become due to RIL if it can legally prove that Dhirubhai-1 and 3 gas output dropping to a tenth of projected 80 million cubic meters per day was due to geological reasons, and not because of hoarding.     

Sources said RIL has written to the Oil Ministry saying it is entitled to getting the principal amount together with market interest rate in case it wins the legal case.

The new gas rates came into effect from November 1 and following the fortnightly invoicing practice, first bill at the new price were raised on November 16.

The bills asked users to deposit USD 4.2 with KG-D6 partners RIL, BP and Niko in 60:30:10 proportion of their shareholding and the rest into GAIL-operated gas pool account.

Sources said RIL and its partners are paying the government statutory levy of royalty at the rate of 5 percent of the USD 4.2 gas price they got but it is unclear who will make the payments on USD 1.41/unit flowing into the gas pool.

The partners want GAIL to invest the USD 1.41/unit, which amounts to about USD 4 million every fortnight, in good interest bearing instruments.

They will claim the principal together with interest if they win arbitration or else the government too may get some extra income, sources said.

Sources said RIL had originally suggested that it should be allowed to collect the new rate of USD 5.61 and promised to pay royalty on the full amount and deposit the USD 1.41/unit in the gas pool account within three working days.     

The ministry, however, went by two-part payment system which is fraught with risks like payment defaults.

GAIL, not being either party to the Production Sharing Contract government signed with RIL for KG-D6 block, or the Gas Sales and Purchase Agreement (GSPA), cannot enforce timely payments of USD 1.41/unit from the users, who are primarily fertilizer plants.

As part of GSPA, RIL has secured from the buyers payment sureties in form of bank guarantees which it can encash if payments are not made. No such instrument, however, is available with GAIL.

Latest News  from Business News Desk