In a statement, the Arvind Kejriwal-led party also hit out at the UPA government, saying the SG's opinion was "shocking" and "clearly establishes collusion between the petroleum ministry and the Reliance Industries". It wondered whether the UPA government was using him to "avoid facing the law, once it is out of power".
"What is surprising is that the SG has used the language quite similar to that of the BJP leadership in raising a false and unjustified bogey of federalism in their combined attempt to bail out the RIL and support the petroleum ministry's move to double the prices of natural gas.
"The SG's opinion raises serious questions about professional ethics also. He is the same law officer, who on April 3 tried to defend the Centre's decision to double the prices of natural gas before the Supreme Court," AAP said.
Kejriwal-led Delhi government had registered an FIR against Union Petroleum Minister Verrappa Moily and Mukesh Ambani led Reliance Industries for alleged irregularities in the KG basin gas pricing issue.
Parasaran's opinion was sought by the Centre which is working on a way to end the controversy.
In his opinion, Parasaran said the "course of action" adopted by Arvind Kejriwal government is against the federal structure of the country. But he has cautioned that the Delhi Lieutenant Governor should not take steps to get the FIR declared as "non est" (non-existent).
The AAP today also questioned the timing of the opinion given by SG and asked why was it had come nearly two months after the FIR was lodged.
"(This) raises suspicion that the UPA government, which is about to demit office in a month's time is using its law officers to avoid facing the law, once it is out of power.
"What was least expected from a law officer was to have taken into account the fact that the Election Commission has deferred the central government's decision to double the prices of natural gas from April 1," the statement added.
"The opinion by a central government's law officer (Solicitor General) reported in the media is shocking and clearly establishes collusion between the petroleum ministry and the Reliance Industries Limited, which is aimed at providing this company an unjustified gain of Rs 54,500 crore every year.
"The Solicitor General (SG) appears to be trying to create an erroneous impression that even if any central minister allegedly commits a crime in Delhi, then no action can be taken against such a minister," the statement added.