Earlier, a single-member Bench of the high court had given a similar order, against which NTPC had filed an appeal.
A Division Bench led by Chief Justice Swatenter Kumar on Thursday dismissed NTPC's appeal.
The suit between the two parties relates to their gas supply agreement.
RIL through the proposed amendment wants to bring on record the affidavit filed by the central government in the RIL-RNRL case in the high court last year and to take a stand that RIL's bid for NTPC tender stands frustrated due to the government's policy.
The high court has given NTPC four weeks to appeal in the Supreme Court.