KEY WEST, Fla. -- The Coast Guard says the tar balls found off Key West aren't linked to the Gulf of Mexico oil spill.
A report released Wednesday says tests show the tar balls don't match the type of oil from the Deepwater Horizon spill. The source of the tar balls isn't known. Tar balls can occur naturally or come from other sources such as ships.
Twenty were found Monday and several others Tuesday.
Scientists are anxiously awaiting signals about where the massive oil slick may be heading, while containment of the looming environmental catastrophe proves elusive.
With fears growing that the gushing well could spread damage from Louisiana to Florida, Interior Secretary Ken Salazar told a Senate panel Tuesday that his agency had been lax in overseeing offshore activities and that may have contributed to the disastrous spill.
"There will be tremendous lessons to be learned here," Salazar said in his first appearance before Congress since the April 20 blowout and explosion on the Deepwater Horizon rig that killed 11 people.
Coast Guard Adm. Thad Allen told another committee that the growing size and scattershot nature of the spill were creating "severe challenges" in containing it and cleaning it up. He called it more complicated than any spill he's ever seen.
"What we're basically trying to do is protect the whole coast at one time," Allen said.
The House Transportation and Infrastructure Committee was set to address the spill at a hearing Wednesday.
Government scientists were surveying the Gulf to determine if the oil had entered a powerful current that could take it to Florida and eventually up the East Coast.
Questions remained about just how much oil is spilling from the well, and senators expressed frustration about a lack of answers during a full day of hearings that included top executives from BP PLC, the oil giant that leased the blown well, and Transocean Ltd., the rig owner.
New underwater video released by BP showed oil and gas erupting under pressure in large, dark clouds from its crippled blowout preventer on the ocean floor. The leaks resembled a geyser on land.
Salazar promised an overhaul of federal regulations and said blame rests with both industry and the government, particularly his agency's Minerals Management Service.