"Markey, D-Massachusetts, said in a letter to BP that scientific evidence showed such plumes have formed, and he asked for BP CEO Tony Hayward to provide evidence to back up Hayward's claim Sunday that the oil had gone to the surface.
On Sunday, Markey, who heads the House Energy and Environment subcommittee, accused BP of issuing false statements about the spill.
"BP in this instance means 'Blind to Plumes,' " Markey said in a statement Monday. There was no immediate response from BP."