Mangalore Refinery and Petrochemicals Ltd (MRPL) paid about USD 183 million (Rs 1,128 crore), Essar Oil USD 172 million, Indian Oil Corp (IOC) USD 41 million and Hindustan Petroleum Corp Ltd (HPCL) USD 4 million, industry sources said.
Another USD 500 million are due to be paid within this month, they said.
The USD 900 million payment will be on top of USD 1.65 billion the refiners had paid in June/July. Cumulatively, refiners owe about USD 6 billion to Iran.
This was in addition to USD 4.2 billion Iran had received between January and July.
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Of the USD 2.8 billion, USD 900 million was to come from India, sources said.
Iran and the United States, China, France, Germany, UK and Russia had in July agreed to extend a six-month interim accord until November 24 pending a long-term deal to end their nuclear dispute.
Sources said the USD 900 million has to flow out before November 24.
Indian refiners had paid the previous USD 1.65 billion in three equal instalments of USD 550 million each - first on June 26, second on July 8 and third on July 24.
Since February 2013, when the US blocked payment channels to Iran for its nuclear programme, India has been paying 45 per cent of its Iran oil bill in rupees through a UCO Bank branch in Kolkata. For the remainder, it had been waiting for a way to make the payment.
Sources said the payment mechanism used in June/July will again be used to clear USD 400 million dues.
Rupee payments equivalent to USD 400 million will be deposited by Indian refiners in the UCO Bank account, which will now be transferred to the Reserve Bank of India for onward credit to the central bank of the United Arab Emirates, which will make payments in dirhams to Iran.
Since July 2011, India had been paying in euros for 55 per cent of its purchases of Iranian oil through Ankara-based Halkbank. The remaining 45 per cent was remitted in rupees through UCO Bank.