Cairn Energy last year sold a controlling stake in Cairn India to London-listed miner Vedanta Resources in an $8.7bn deal. The British oil firm owned nearly 22 per cent of the Indian company as of 31 March.
In June, Cairn Energy sold 3.5 per cent of Cairn India to raise about $360bn.
Cairn Energy held 18.3 per cent of Cairn India as of the end of June, stock exchange data showed. After its latest share offering, its stake will fall to about 10 per cent.
Cairn Energy yesterday launched an offering of nearly 153m shares of Cairn India for between 317.90 rupees and 328.30 rupees per share, said the source, who asked not to be identified as he was not authorised to speak to the media. Citigroup is acting as sole bookrunner.