Smoke rises from the BP oil spill site as natural gas is burned off, while the drilling of two relief wells continues in the Gulf of Mexico on Sunday. (Lyle W. Ratliff/Reuters)

BP says it has spent more than $3 billion US responding to the growing oil spill in the Gulf of Mexico.

The oil company said in a statement Monday that is has spent $3.12 billion so far in responding to the spill. The costs include attempting to contain oil, paying claims and reimbursing the U.S. and local governments.

The company said it has spent $147 million settling 47,000 claims — about half the claims submitted so far. The figures provided Monday do not include a $20-billion fund for Gulf damages BP created last month.

BP bills partners

At the same time, BP is billing partners Anadarko Petroleum Corp. and Japan's Mitsui for their shares of the cleanup.

BP has billed Anadarko for more than $250 million US so far. Anadarko, based in Woodlands, Texas, is a 25 per cent stakeholder in the well.

BP is also reported to have billed Mitsui, a 10 per cent partner, for $111 million.

"They are partners in the field, and as responsible partners we would expect them to bear some of the costs," BP spokeswoman Sheila Williams said Monday.

Anadarko said in a statement it is reviewing the bill sent last week and "assessing our contractual remedies."

Anadarko CEO Jim Hackett argued last month that his company should be excluded from paying for the spill due to BP's "reckless decisions and actions" in its handling of the well.

Hackett accused BP of failing to "react to several critical warning signs" as it drilled below the sea floor.

Calls to Mitsui & Co. for comment weren't immediately returned.

Cleanup continues

Bad weather and rough seas have forced officials to wait for results from a new oil skimming vessel deployed over the weekend.

The Taiwanese vessel, dubbed A Whale, is 10 storeys high and longer than three football fields. BP and the U.S. Coast Guard are waiting to see if it can live up to its maker's promise of being able to process up to 76 million litres of oil-fouled water a day.

BP workers in Cocodrie, La., pile booms that have been cleaned and repaired for reuse after they were stained with oil from the spill in the Gulf of Mexico. (Judi Bottoni/Associated Press)

TMT, the shipping firm that owns the vessel, had hoped to test a containment boom system designed to direct greater volumes of oily water into the 12 vents or "jaws" the ship uses to suck it in, according to spokesman Bob Grantham.

But stiff winds and choppy seas have made that impossible, and have also prevented a flotilla of smaller skimmers from working offshore along the coasts of Alabama, Mississippi and Florida.

"As was the case yesterday, the sea state, with waves at times in excess of 10 feet, is not permitting optimal testing conditions," Grantham said in an email Sunday.

The smaller skimmers, which have been idle off the coasts since a spell of bad weather last week kicked up by Hurricane Alex, were on the water along the Louisiana coast over the weekend. Officials with the U.S. Coast Guard are waiting for the weather to improve before sending them elsewhere.

"We've got our guys out there, and they're docked and ready, but safety is a huge concern for us, especially with the smaller vessels," said Courtnee Ferguson, a spokeswoman for the Joint Information Command in Mobile, Ala.

Cleanup efforts continue, with more than 44,500 people working on the response effort, BP said Monday. Two containment systems are collecting oil and gas flowing from the blown out well, and the drilling of two relief wells continues despite rough seas, the company said.

The spill in the Gulf of Mexico began after an oil rig exploded off the Louisiana coast, killing 11 workers and sparking a massive underwater leak.

With files from The Associated Press