The oil disaster in the Gulf of Mexico has so far spewed 2.3-4.5 million barrels of crude into the sea, the International Energy agency estimated on Tuesday as BP fought to staunch the flow.
The agency also said that it was cutting its estimate of US oil production from the Gulf of Mexico by about 30,000 barrels per day for 2010 and 2011 "because of delays following the Deepwater Horizon (rig) disaster."
The IEA, the oil strategy arm of the Organisation for Economic Cooperation and Development, said in its monthly review of the oil market: "Project delays could further curb future US supply if wide-reaching drilling restrictions arise from the disaster enquiry."
However, the agency also said that for the whole of 2011 it estimated "an incremental 55,000 barrels per day of crude oil from the US Gulf of Mexico, despite evidence of slowing down there as the uncertainty surrounding the deepwater drilling moratorium begins to have an impact on new upstream projects
The IEA continued: "Until more clarity prevails over new regulatory and operating procedures and whether the deepwater drilling moratorium will stay in place, we refrain from including a broader downward adjustment to our US production forecast.
"But extended project delays, if they occur, could reduce our 2015 projection for US Gulf production by 100,000-300,000 barrels per day."
The agency said that at the time it wrote its report, 60,000 barrels per day of crude oil were estimated to be flowing from the stricken wellhead of which about 25,000 barrels per day had been siphoned into containment systems, and about one third, together with gas, had been flared or burnt off.
"The other two thirds have been collected, cleaned and sent ashore."
It said: "We estimate that something in the range of 2.3-4.5 million barrels of crude oil have been spilled in total, excluding the volumes contained, making this the largest oil spill in US history."