ON THE GULF OF MEXICO (AP) - A Coast Guard official says tar balls that are believed to be from the Gulf of Mexico oil spill are washing up on an Alabama island.

Coast Guard chief warrant officer Adam Wine said about a half dozen tar balls had been collected by Saturday afternoon at Dauphin Island.

He says the substance needs to be tested, but officials think it came from the oil spill.

The barrier island is at the mouth of Mobile Bay and about three miles from the coast.

Word of tar balls washing ashore came as a BP PLC official said that icelike crystals were causing problems with an oil containment box that had been placed over the massive leak about 50 miles from the Louisiana coast.

BP chief operating officer Doug Suttles says it will probably take the next two days to study the problem.