Section 84
When foreign States may sue
Part IV: Suits in particular cases
A foreign State may sue in any competent Court:
Provided that the object of the suit is to enforce a private right vested in the Ruler of such State or in any officer of such State in his public capacity.
The Code of Civil Procedure, 1908 (Act No. 5 of 1908). From the updated text on India Code, with later amendments. Being checked against the official copy; amendment notes are not shown yet.