First moving pictures of BP's oil leak

The public has seen for the first time the extent of the oil gushing from BP's broken pipe nearly a mile under water.

The oil giant has released a video taken by a remote-controlled camera.

Over the past 21 days more than four million gallons of oil have been released since the Deepwater Horizon exploded in the Gulf of Mexico.

Speaking at a news conference on Wednesday, BP Chief Operating Officer Doug Suttles said that the flow rate looked "pretty much the same as it's always looked".

"It may have a bit more of this white element to it, which may or may not mean that the flow rate is reduced slightly," he added.

Meanwhile, a new containment box - a cylinder called a "top hat" - was placed on the sea floor near the well leak. Engineers hope to work out ways to avoid the problem that scuttled an earlier effort with a much bigger box before they move the cylinder over the end of the 5,000-foot-long pipe from the well.

The 100-ton box filled up with an ice-like slush of gas and water, lifting it up and clogging its nozzle.

BP has another plan it might try to siphon oil away from the unchecked well.

Suttles said that engineers hope to link a second pipe to the end of the pipe that was supposed to pump oil from the sea floor before the Deepwater Horizon sunk.