U.S. President Barack Obama announced Saturday that former Florida senator Bob Graham and former EPA administrator William Reilly will lead a presidential commission investigating the Gulf of Mexico oil spill.

Officials sent out the U.S. Army National Guard to erect barriers on some beaches in Alabama to try to protect the shoreline. Here, a barrier can be seen along the northern shore of Dauphin Island, Ala. (Jay Reeves/Associated Press)

Obama said the spill "has not only dealt an economic blow to Americans across the Gulf Coast, it also represents an environmental disaster."

In his weekly radio and internet address, Obama said he wants the panel to report back in six months on ways to prevent future offshore drilling accidents.

"I want to know what worked and what didn't work in our response to the disaster, and where oversight of the oil and gas industry broke down," he said.

Graham, a Democrat, is a former Florida governor and senator. Reilly ran the Environmental Protection Agency under Republican president George H.W. Bush. His tenure at the agency included the 1989 Exxon Valdez oil spill in Alaska.

"I can't think of two people who will bring greater experience or better judgment to the task at hand," Obama said.

Obama intends to name five other people to the panel, which will examine everything from what caused the spill, to the safety of offshore drilling generally, to operations at the Minerals Management Service, the federal agency that grants drilling rights.

"We need to do a lot more to protect the health and safety of our people, to safeguard the quality of our air and water, and to preserve the natural beauty and bounty of America," Obama said. He added that he wants "a comprehensive look at how the oil and gas industry operates and how we regulate them."

Hundreds of thousands of litres of oil continue to pour daily into the gulf from the wellhead 1.5 kilometres beneath the surface. The massive spill threatens beaches, marshes, fisheries and wildlife.

The spill began April 20 when the BP-leased Deepwater Horizon drilling rig exploded off the Louisiana coast, killing 11 workers and rupturing an underwater pipe.

BP said it will be at least Tuesday before engineers can shoot heavy mud into the blown-out well on the seabed in an effort to clog it.

Engineers had hoped to try the so-called "top kill" as early as this weekend, but the company said it needed more time to test the procedure.

With files from The Associated Press