Section 31(7)(a) in The Arbitration And Conciliation Act, 1996
(a)Unless otherwise agreed by the parties, where and insofar as an arbitral award is for the payment of money, the arbitral tribunal may include in the sum for which the award is made interest, at such rate as it deems reasonable, on the whole or any part of the money, for the whole or any part of the period between the date on which the cause of action arose and the date on which the award is made.