Top industry sources disclosed that Marathon has also been shortlisted in the first round of bidding along with Reliance and ONGC for buying Enron's stake in these fields.

Whereas, both Reliance and ONGC are part of the consortia already developing these fields, Marathon is the only company which has been shortlisted outside the consortia.

"Currently, Marathon is doing the due diligence of Enron's assets following which it will submit the financial bids along with other shortlisted parties," the sources said.

Sources informed that Marathon possesses some of the best oil and gas exploration technologies in the world, and, at one point of time, even ONGC was in talks with Marathon for acquiring its technology.

Asked if there was any possibility of ONGC and Marathon joining hands for submission of financial bids, industry sources said both the companies have decided to bid independently.

Moreover, for all these discovered fields, ONGC does not require any financial or technical support from others. Reliance, however, is not qualified to be the operator of oil and gas fields as it does not have sufficient experience in the area.

On the other hand, Marathon possess strong technical skills in this area and, if selected, can easily qualify as an operator.ONGC is the biggest partner in the consortium in terms of its equity stake.

It has 40 per cent with the remaining 60 per cent, shared equally between Reliance Industries and Enron Oil and Gas India.

However, Enron is the operator of this $900 million joint venture between Reliance and ONGC. Both ONGC and Reliance have the pre-emption rights by virtue of being partners in the joint ventures operating these companies.

But this does not mean that they will get it any cheaper. They will have to match the highest bidder, sources said.

It may be recalled here that Enron has recently decided to sell its entire oil and gas assets in India. The buyer for these assets is to be selected through a two-stage bidding process.

Credit Suisse First Boston has been appointed as the investment banker to derive current value of its stake in the joint venture. These oil and gas fields in Gujarat and Mumbai offshore are reportedly producing around 300 million cubic metre of gas and 29,000 barrels of oil per day.