Indian Oil Corporation (IOC), the nation's largest refiner, has lost out in the race for acquiring French company Maurel & Prom's stake in oilfields in Congo.Burren Energy of UK, which was supposed to exercise its pre-emption rights to stop the sale of M&P's stake in Congo fields to Italy's Eni Spa and instead get IOC in the French company's shoes, has dumped the Indian firm after reaching an agreement with Eni, a company source said.Eni will sell 5.5% out of the 48.6% M&P stake it is acquiring in the 56,000 barrels per day M'Boundi oil field and 2% out of the 50% M&P interest it is taking over in the surrounding Kouilou exploration license for $154 million."Originally, Burren Energy, which had 31.5% stake in M'Boundi field and 35% interest in Kouilou was opposed to M&P selling its stake to Eni. Burren wanted operatorship of the fields and was in advanced stage of talks to rope in IOC and its partner Oil India after it stopped the sale by exercising pre-emption rights," the source said.The IOC-OIL combine had no problems with Burren taking over operatorship and they had even agreed to assign a portion of the M&P stake to the UK firm. Burrent, however, reached an agreement with Eni earlier this week where the Italian firm will retain the operatorship.M&P had, on February 22, announced sale of its 48.6% stake in the producing fields of M'Boundi and 50% out of the 65% interest in Kouilou to Eni for $1.434 billion. Also included in the sale was M&P's 66.7% stake in the Kouakouala field.