British oil major BP said the oil spill in the Gulf of Mexico had cost it $450 million so far, an increase of $100 million on the figure reported earlier this week.
Analysts forecasts for the clean-up costs and compensation for the spill off the coast of Louisiana have ranged from a few hundred million dollars to over $12 billion.
The updated estimate came as BP said it was preparing to try to staunch the flow of oil from the ruptured well using a small containment dome, although said there was no guarantee of success given the difficulties of working almost a mile under the ocean surface.
The $450 million includes the cost of spill response, containment, relief well drilling, commitments to the Gulf Coast States, settlements and federal costs, BP said in a statement.
It said 6,700 claims have been filed, of which about 1,000 have already been paid.
A spokesman for BP said the run rate was around $10 million per day in terms of the surface and subsea spill response.
This number strips out non-daily and one-off costs such as the grants of $25 million each paid to four states to jump-start clean-up projects.
BP had originally estimated the daily run rate at $6 million on May 4, but said then that the rate was rising.
Shares in BP have tumbled since the Deepwater Horizon rig caught fire on April 20, wiping about $30 billion of its market value but the stock was up 0.13 percent at 542.6 pence at 0950 GMT.
It looks like the shares have temporarily found a floor, but any setbacks on the ocean floor could undermine confidence, said Evolution Securities analyst Richard Griffith.
(Reporting by Victoria Bryan; Editing by Hans Peters)