Shares in the gas utility traded with over 4 per cent gains at Rs 78 on the BSE because the order is applicable only for high pressure network against expectation for both high and low pressure networks.
GSPL's one-time liability is seen between Rs 300-600 crore.
Global brokerage firm Nomura said compared to PNGRB's earlier tariff decision, this order appears soft.
Domestic brokerage Religare said the approved tariff was in-line with expectations. Religare has a "hold" rating on GSPL.
The approved rate would be effective November 20, 2008, PNGRB said, adding the difference between the tariff charged and that approved by the board shall be adjusted with customers in future billings. PNGRB also directed GSPL to return the cost of entire system use gas (SUG), including unaccounted gas to the shippers/consumers from November 20, 2008 onwards and withdraw separate recovery either in cash or in kind with immediate effect.
(With inputs from PTI)