Tar balls that turned up on the US Gulf coast this month are linked to BP's oil spill last year, signalling that the area is still not fully cleaned up, a study has found.
Researchers from Auburn University found the environmental impact of the spill is continuing 17 months since oil leaked into the ocean, after an explosion on the Deepwater Horizon.
They found that "mats" submerged in the seabed for more than a year had been broken up by tropical storms and gave off the tar balls.
The pollution found on Alabama beaches this month had "essentially identical" chemical composition to those from after the spill.
Researchers now "question the validity of the widely-held belief that submerged oil from the Deepwater Horizon accident is substantially weathered and depleted".
BP said it would "continue to have crews out collecting tarballs as the reports come in" but the report would not change its immediate plans. more