However, RNRL gained about three per cent on the bourses, while shares of Reliance Energy [Get Quote], another Anil Ambani group firm also firmed up by more than five per cent. Shares of state-run NTPC and Petronet LNG [Get Quote] also gained ground.

Petronet LNG is the only major company importing natural gas into India and might benefit in terms of larger number of customers if RIL is barred from selling the gas to third parties, analysts believe.

The Bombay High Court has asked RIL not to sell the natural gas to be produced from its KG basin block in Andhra Pradesh to third parties except NTPC and RNRL for the first eight years starting 2008. RIL plans to begin production from the block in July 2008, with initial output of close to 40 million standard cubic metre (mscmd) of gas per day.

Peak output would touch 80 mscmd later. Shares of RIL dropped 1.7 per cent or Rs 29.10 a share to close at Rs 1,704.05, after hitting an intraday low of Rs 1,696.60 on the BSE. RNRL gained 3.09 per cent to close at Rs 35.05, after hitting an intraday high of Rs 36.90.

It was the most traded counter on both BSE and NSE with a collective volume of over 2.5 crore shares changing hands on the two exchanges. Analysts at domestic brokerage firm Anand Rathi said that RIL could see some negatives on the back of the court ruling, while this could bring gains for RNRL on the other hand.