The government on Friday said a formal policy on the usage of surplus coal produced in mines allocated for captive use to companies would be finalised in a month.

This follows a controversy over the government's decision to allow Reliance Power to divert surplus coal from mines allocated for the Sasan ultra mega power project (UMPP) for use in another project. The Comptroller and Auditor General (CAG) of India, in its leaked draft report, had recently alleged the decision led to “undue benefits” of Rs 15,849 crore to the Anil Dhirubhai Ambani Group subsidiary.