The logo of Oil and Natural Gas Corp's (ONGC) is pictured along a roadside in Ahmedabad, India, September 6, 2016.
The comments come after India's finance minister announced a plan this year to provide equity of 300 billion rupees ($3.6 billion) to help the big state oil refiners move towards cleaner energy.
Based on rights issues previously announced by two other state refiners, an ONGC issue could amount to about 155 billion Indian rupees ($1.86 billion), Reuters calculations show.
ONGC, HPCL and the oil and finance ministries did not immediately respond to requests for comment.
India's other big state refiners, Indian Oil Corp (IOC.NS) and Bharat Petroleum Corp (BPCL.NS) have announced plans to launch rights issues of 220 billion and 180 billion rupees, respectively.
Persons:
Amit Dave, ONGC, Nidhi Verma, Tony Munroe, Clarence Fernandez
Organizations:
Gas, REUTERS, Natural Gas Corp, Hindustan Petroleum Corp, Indian Oil Corp, Bharat Petroleum Corp, IOC, Thomson
Locations:
Ahmedabad, India, DELHI, New Delhi, HPCL, ONGC, BPCL