Major progress in British oil major BP's fight against the weeks-long Gulf oil spill may come soon with a third oil-capture vessel and a new containment cap expected to be put in place as early as this weekend, the US commander for the spill said Friday.

BP currently captures about 28,000 barrels of oil a day from the blown-out well in the Gulf of Mexico, largely by two vessels, the Discoverer Enterprise and the Q4000. A new oil-recovery vessel, the Helix Producer, could be hooked up to the underwater gusher Friday, thanks to a good "weather window", retired Coast Guard Admiral Thad Allen, the US national commander for the spill, said Friday.

The vessel is intended to increase oil-capture capacity to 53, 000 barrels a day. The ship is expected to start siphoning oil by Sunday, Allen said. Meanwhile, Allen said, the current containment cap "can be removed quite quickly" and BP could start replacing it with a larger and more permanent new sealing cap as early as Saturday.

There should be three to four days before crews can put the new cap in place as special tools are needed to switch out the cap, Allen said. Once the new cap is installed, BP and US government scientists should have accurate data on how much oil is leaking, according to Allen.

US government scientists have estimated 35,000 to 60,000 barrels of oil are gushing into the Gulf of Mexico a day. The spill, the worst in US history, began April 20 with an explosion and fire aboard the BP-leased Deepwater Horizon drilling rig off the Louisiana coast, killing 11 workers. So far, the spill has reached all five US Gulf states, costing BP more than 3 billion US dollars to clean up the Gulf.