Before acquisition by ONGC in March 2003, MRPL, was a joint venture Oil Refinery promoted by M/s Hindustan Petroleum Corporation Limited (HPCL), a public sector company and M/s IRIL & associates (AV Birla Group). MRPL was set up in 1988 with the initial processing capacity of 3.0 Million Metric tonnes per annum that was later expanded to the present capacity of 15 Million Metric tonnes per annum. The Refinery was conceived to maximise middle distillates, with capability to process light to heavy and sour to sweet Crudes with 24 to 46 API gravity. On 28th March 2003, ONGC acquired the total shareholding of A.V. Birla Group and further infused equity capital of Rs.600 crores thus making MRPL a majority held subsidiary of ONGC. The lenders also agreed to the Debt Restructuring Package (DRP) proposed by ONGC, which included, interalia, conversion upto Rs 365 crore of their loans into equity. Subsequently, ONGC has acquired equity allotted to the lenders pursuant to DRP raising ONGC's holding in MRPL to 71.62 percent.
The implementation of DRP in March 2003 within 4 weeks of acquiring equity in MRPL by ONGC has changed the credit profile of the company. ICRA has assigned A1+ rating (indicating highest safety) to the Short Term Borrowing programme of MRPL on a standalone basis