Highly placed sources in a state owned insurance company, confirming the claim amount, termed it the single largest claim by any company in the country.
The claim has already reached the insurance and reinsurance companies and they are working on it, said sources.
ONGCs oil platform is insured for $750 million with $20 million deductible, which means ONGC has to absorb losses up to $20 million on its own balance sheet.
ONGC, which has the countrys largest insurable assets, had insured with Chennai-based United India Insurance, which had shared the risks with other state-owned and private sector general insurance companies.
ONGCs assets are reinsured up to 95% with state-owned General Insurance Corporation (GIC) and the reinsurance market in London.
It is believed that the energy major needs around $500 million to repair the damaged platform out of which it can now recover 50% from reinsurance companies.
However, it is unlikely that ONGC will get the entire claim amount.