Coastguard Rear Admiral Mary Landry oiutlines rthe scale of the Gulf of Mexico oil slick Reuters

Five times more oil a day than previously believed is spewing into the Gulf of Mexico from the blown-out well of the Deepwater Horizon drilling rig, the US coastguard has said.

Coastguard Rear Admiral Mary Landry said National Oceanic Atmospheric Administration (NOAA) experts now estimate that 5,000 barrels a day of oil are spilling into the gulf – far more than the previous estimate of 1,000 barrels a day. Robot submarines have so far failed to shut off the flow, 1,500m (5,000ft) below the surface, but the coastguard said a test burn on an isolated area of the spill was successful.

The revision came after a new leak was discovered and strong winds were forecast which NOAA said would push the oil towards the US shoreline.

However Doug Suttle, chief operating officer for BP, disputed the new estimates yesterday, pointing to a diagram that plotted the leaks and saying he did not believe the amount of oil spilling into the water was higher than earlier approximations.

Landry stuck to the NOAA estimate and said it was based on aerial surveys, study of the trajectory of the oil slick and other factors.

Landry added that the US president, Barack Obama, had been briefed on the revised estimate, and said the government had offered to have the defence department help contain the spill and protect the US shoreline and wildlife.

Both Landry and BP said the first test burn had been successful, although neither gave any indication as to when further burns were planned.

Crews had planned to use a 150m fire-resistant boom to collect several thousand gallons of the thickest oil on the surface, tow it to a remote area, set it on fire, and allow it to burn for about an hour. When the flames go out hardened tar is left in the water, which can be removed using nets or skimmers.

BP said more than 30,000m of boom had so far been assigned to contain the spill, with an additional 87,000m available and 97,000m on order.

The oil spill response team had recovered 16,311 barrels (2.5m litres) of an oil-water mix, and 69 response vessels were being used, the company added.

"We are attacking this spill on all fronts, bringing into play all and any resources and advanced technologies we believe can help," said Tony Hayward, BP chief executive.

"Our action plan is safety-focused, multi-layered and has the full resources of the BP Group behind it."

He added: "The scale of the surface response is truly unprecedented, both for BP and for the oil industry."

BP said it had begun preparations to drill a relief well, approximately half a mile from the main well, however NOAA said this would not be complete for several months.

NOAA said workers had finished fabricating the containment chamber of a "collection dome" which would be used to collect oil as it escaped from the well.

"Work will now begin on the piping system that brings the oil to the surface for collection; this method has never been tried at this depth before," the organisation said.

It said evaluations were under way to assess the damage caused by the oil to fish, marine mammals and sensitive resources, and warned the spill was on the move.

"Winds are forecast to become strong (20+ knots) and blow from the south-east starting tomorrow and continuing through the weekend, which will continue to push surface oil towards shore," NOAA said.

BP said costs for containing the spill were running at $6m (£3.9m) a day, and it would spend a further $100m drilling the relief well. Industry officials say replacing the Deepwater Horizon, which was owned by Transocean Ltd but operated by BP, would cost up to $700m.