BP Plc said on Monday it had incurred $350 million in costs so far from the huge oil spill in the Gulf of Mexico as fears mounted of a prolonged and growing environmental and economic disaster.

BP was considering its next move to contain the spill after its most promising short-term remedy struck a snag over the weekend.

Its shares fell about 1 percent in early trade in London against a 2.5 percent rise in the European oil sector index. BP’s value has been savaged by investors since the crisis erupted last month.

The uncontrolled spill, which could become the worst in U.S. history, is expected to drift farther west, away from Florida’s popular beaches but into the important shipping channels and rich seafood areas off the central Louisiana coast, west of the Mississippi Delta.