LONDON (MarketWatch) -- Oil giant BP BP, -0.51% BP, -1.18% said Friday that it may take a further 24 to 48 hours to complete the "top kill" procedure on the oil leak in the Gulf of Mexico. If the well is successfully killed then cementing operations would follow, the group added. BP said the cost of the response to date is around $930 million and that it has made payments on 11,650 of the roughly 26,000 claims that have been received so far. The company said almost 1,300 vessels are now involved in the response effort and that operations to skim oil from the surface of the water have recovered 274,000 barrels of oily liquid.