LONDON (MarketWatch) -- BP on Thursday stemmed the flow of its tumbling share price if not the flow of oil in the Gulf of Mexico, after saying it couldn't explain why its share price plunged by 16% in the last session of New York trade.

The oil giant BP, -1.18% (BP), which has failed to stop a massive Gulf spill that began more than six weeks ago, got slammed in U.S. action following fresh criticism by President Barack Obama, who said he would have fired Tony Hayward by now if the BP CEO instead worked in his administration.

The plunge, taking the market capitalization reduction to $90 billion since the Deepwater Horizon sank, also came as several U.S. politicians called on BP to halt payment of its dividend. See related story.

BP, making the first defense of its share price, on Thursday said it's facing the crisis "as a strong company," noting that until the spill, cash inflows and outflows were balanced with oil prices at $60 a barrel. Oil has been trading around $75 a barrel of late, meaning the company's "generating significant additional cash flow."

Its gearing -- the ratio of net debt to equity -- also is below the bottom of BP management's targeted range. Plus, it has more than 18 billion barrels of proved reserves and 63 billion barrels of resources as of the end of 2009, BP said.

"All of the above gives us significant capacity and flexibility in dealing with the cost of responding to the incident, the environmental remediation and the payment of legitimate claims," the company said.

Its pleas did make an impact. BP's London-listed (BP) shares dropped 7%, a fall not nearly as severe as that was seen in New York.

In opening U.S. trades on Thursday, BP shares rallied 9%.

Sell-side analysts have largely agreed with the company that the plunge in BP's share price has been excessive. Two-thirds of the analysts who cover BP have buy or overweight ratings, with an average target price of $56.97, according to data compiled by FactSet Research.

For the long term, "we still believe BP is undervalued and that the market is now discounting the worst case rather than most likely outcome. We would buy the stock, realizing that near term, BP will continue to be buffeted by negative speculation, at least until it can be more informative about costs," said analysts at Citigroup.

However, S&P Equity Research lowered BP to hold from buy, citing uncertainties swirling around the Gulf accident, political sensitivities regarding BP keeping its 2010 dividend, the costs of cleaning up, upcoming civil charges and potential U.S. government resolutions.

The overall cost of the response to date is $1.43 billion, BP said, a figure that includes the containment, relief well drilling, grants to the Gulf Coast states, claims paid, and federal costs. This also includes the first $60 million in funds earmarked for the Louisiana barrier islands construction project.

The lower marine riser package containment cap collected 15,000 barrels of oil and 29.4 million cubic feet of natural gas on Tuesday, and in the first 12 hours of Wednesday, collected 7,920 barrels and 15.7 million cubic feet of natural gas.