BP Plc is ready to switch caps at the wellhead of the gushing Gulf of Mexico leak to create a hurricane-ready system that can capture more oil, the top official overseeing the spill response said on Thursday.

U.S. Coast Guard Admiral Thad Allen said BP and government officials would decide in the next 24 to 48 hours whether to switch caps, which would allow crude to leak unchecked in the interim.

The switch also would increase BP's siphoning capacity to 80,000 barrels a day among four vessels that could disconnect and move fast if a hurricane approaches.

BP is in position at this time to move forward, he said.

In Washington, a U.S. official said the White House is sending BP a list of questions about its efforts to cap the well and ordering the company to respond within 24 hours.

Allen also said the first of two relief wells intended to intercept and plug the leak should bore into the stricken wellbore in seven to 10 days.

But he said the plugging process could be lengthy, so the target date remains early to mid August rather than this month.

In related developments:

* Allen said seas at the leak site were calm enough to allow BP in the next day or two to finish hooking up a third oil-capture vessel to increase siphoning capacity of 28,000 barrels a day to 53,000.

* Allen said BP could switch caps while hooking up the third siphoning vessel.

* The relief well reached 12,780 feet beneath the seabed, or 220 feet from the bottom of BP's blown-out well.

* BP's current oil-capture systems collected or burned off 24,575 barrels of oil on Wednesday.

(Reporting by Kristen Hays; Editing by Vicki Allen and Jerry Norton)