LONDON — BP said today that the Gulf of Mexico oil spill has cost the company $350 million so far as it outlined renewed efforts to contain the leak.

BP said the tally included the cost of the immediate response, containment, relief well drilling, commitments to the Gulf Coast states, and settlements and federal costs.

The company did not speculate on the final bill, which most analysts expect to run into tens of billions of dollars.

The London-based company said that it was preparing a second, smaller containment box to lower over the main leak point at the Deepwater Horizon drilling rig after attempts to do the same with a larger box last week were foiled by icy slush.

BP said the smaller dome was designed to mitigate the formation of the "large hydrate volumes" that clogged the bigger dome.

However, it acknowledged that the maneuver, which is designed to siphon up to 85 percent of the leaking oil to a tanker at the surface, had never been done before in more than 5,000 feet of water. The blown-out well is a mile underwater.