The leaking Gulf oil well has been spewing 25,000 to 30,000 barrels of oil a day, more than previously estimated, a team of U. S. scientists has said.

The Washington Post reported on Thursday that the team's data suggest 1.3 million to 1.6 million barrels of oil have leaked since the explosion of the Deepwater Horizon oilrig April 20, roughly five to six times the amount spilled in Alaskan waters in 1989 by the Exxon Valdez.

The White House has said that as BP continues its cleanup efforts, National Incident Commander Adm. Thad Allen sent a letter to BP Chairman of the Board Carl-Henric Svanberg inviting him to meet with President Barack Obama and other senior officials responding to the BP oil spill.

Congress passed a bill Thursday to allow the Coast Guard to draw advances from a trust fund to continue the federal response to the Gulf oil spill. The bill, passed by the Senate on a voice vote on Wednesday, will go to the president for his signature.

The measure would allow "critical" funds to be taken from the Oil Spill Liability fund, but assured taxpayers they would not have to foot the bill, House Majority Leader Steny Hoyer, D-Md., said in a statement released on Thursday.

Hoyer further said, "Taxpayers can be assured that BP and other responsible parties will be billed for all spill containment and cleanup costs."

It is planning additional enhancements to the containment cap on the leaking well as it collects oil and gas in surface ships for transfer to an onshore terminal, BP has said.

Hoses and manifolds from the earlier unsuccessful "top-kill" operation will take oil through a separate riser to a surface vessel to increase the amount being captured, the company further revealed.

CNN also reported on Thursday that oil from the massive spill moved into the inland waterway along coastal Alabama, prompting the U. S. Coast Guard to close Perdido Pass, the main water access route for fishermen and boaters. (With Inputs from Agencies)