WASHINGTON — Workers removed the "top hat" device collecting oil from BP's gushing Deepwater Horizon well Wednesday morning, bringing a halt for much of the day to the primary effort to capture crude escaping into the Gulf of Mexico.

The "top hat" was put back in place nearly 10 hours after it was removed, BP announced.

BP provided only a scant explanation for the sudden removal of the containment device, which was placed atop the well's dysfunctional blowout preventer on June 3.

In a statement announcing that the top hat was back in place, BP said that workers removed it at 8:45 a.m. Central time "as a precaution following observation of an unexpected discharge of seawater from a diverter valve on the Discoverer Enterprise," the drill ship that has been capturing an average of 15,000 barrels a day through the "top hat."

There was no word on what caused the discharge. BP said the "top hat" was reinstalled at 6:30 p.m.

In the hours that the "top hat" was not in place, video from the leak showed crude oil gushing unhindered into the Gulf of Mexico.

Coast Guard Adm. Thad Allen, the Obama administration's point man on the BP oil leak, told reporters in his daily briefing that the Discoverer Enterprise removed the device from the bleeding well after workers detected what appeared to be natural gas coming directly into the ship through a line that was being used to run warm water into the top hat to prevent a buildup of ice-like hydrate crystals. With the ship burning off millions of cubic feet of natural gas each day, workers were concerned the gas might ignite, creating an explosive situation aboard the ship.

Allen said it was unclear how the gas came to be in the warm water line, but that initial suspicions centered on the possibility that a robot vehicle working neaer the top hat had accidentally bumped it and closed one of the vents through which the crude continues to escape. That may have increased pressure within the top hat, forcing gas into the warm water line.

Collection of oil through the Q4000, which draws crude directly from the well's blowout preventer and doesn't depend on the top hat, was unaffected by the incident, BP said.

It was the third time in a week that recovery efforts have been disrupted. Last week, BP shut down collection efforts briefly twice because of lightning, including a bolt that ignited a fire on the Discoverer Enterprise's derrick.