Brent crude fell below 46 dollars yesterday. Court suspended payments under hedge deals last week.
Commercial Bank said the calculation was based on an exchange rate of 110 rupees per US dollar.
Sri Lanka's central bank has been intervening in forex markets since September and injecting more than a 100 million rupees to the inter bank market in a 'sterilized intervention' campaign, bringing a peg with the US dollar under severe pressure.
Sri Lanka units of Citibank, Standard Chartered and Deutsche have also sold derivatives to CPC, but Standard Chartered said last week that the local unit was not affected.
According to a document released to the media last week, Commercial Bank has a sold a target redemption forward on a notional 10,000 barrels of WTI Light Sweet Crude which d