Crude oil from the Deepwater Horizon oil spill washes ashore in Orange Beach, Ala., on June 12. (Dave Martin/Associated Press)

A top U.S. official overseeing efforts to control the Gulf of Mexico oil spill has given BP 48 hours to come up with new plans to contain the leak.

A letter from Coast Guard Rear Admiral James A. Watson, the U.S. government's spill co-ordinator, to BP's chief operating officer says the company's plans for capturing the oil have been overtaken by a new estimate of the size of the leak.

"It is clear that additional capacity is urgently needed," Watson said in a letter to Doug Suttles, dated June 11 and released Saturday. "BP must identify in the next 48 hours additional leak containment capacity."

A U.S. government-created task force, the Flow Rate Technical Group, on Thursday doubled its estimate of the amount of oil leaking from the well, to between 20,000 and 40,000 barrels a day, before a cap was installed on June 3.

The cap is capturing more than 15,000 barrels a day, but large amounts are still gushing into the Gulf.

Watson also had other concerns. BP had indicated some equipment would not be working for a month; Watson said, "every effort must be expended to speed up the process."

He also said BP's plan didn't go far enough in case of equipment failure, or other unforeseen circumstances.

The letter released Saturday is part of an exchange between the company and U.S. government officials that began Wednesday when the Coast Guard asked BP for an update on the company's plans to curtail the oil that has been pouring into the Gulf of Mexico since April 22.

Suttle's June 9 letter to Watson said BP would put in place a "choke line" to catch another 5,000 to 10,000 barrels a day by mid-June, and a "clear line/kill line" that would catch another 5,000 to 10,000 barrels daily by mid-July.