U.S. President Barack Obama announced Saturday the establishment of an independent presidential commission to investigate the huge oil spill in the Gulf of Mexico.

Former senator Bob Graham, a Democrat, and former administrator of the Environmental Protection Agency William Reilly, a Republican, will serve as co-chairmen of the seven-member body, Obama said in his weekly radio and Internet address.

"The purpose of this commission is to consider both the root causes of the disaster and offer options on what safety and environmental precautions we need to take to prevent a similar disaster from happening again," Obama said.

The remaining five members of the panel, which is similar to panels created to investigate the space shuttle Challenger disaster and the nuclear accident at Three Mile Island, will be appointed in coming days. It will include scientists, engineers, and environmental advocates, but no current government employee or elected official.

Obama also made his first reference to the possibility of a separate criminal probe into disaster.

"The commission shall ensure that it does not interfere with or disrupt any ongoing or anticipated civil or criminal investigation or law enforcement activities or any effort to recover response costs or damages arising out of the Deepwater Horizon explosion, fire and oil spill," Obama said.

The Deepwater Horizon drilling rig, owned by Transocean and leased by BP, sank April 22 some 52 km off Venice, Louisiana, after burning for roughly 36 hours. The untapped wellhead continues gushing oil into the Gulf of Mexico.