President Barack Obama on Tuesday vowed to hold the culprits of the US oil disaster legally accountable, and promised to change the law if necessary to prevent history from repeating itself.

Obama delivered the threat after meeting former senator Bob Graham and former Environmental Protection Agency administrator William Reilly, who will co-chair a presidential commission into the Gulf of Mexico oil spill.

Terming the massive spill the "greatest environmental disaster of its kind in our history," Obama said the US government had an "obligation" to find out what caused the explosion of the BP operated Deepwater Horizon rig in April.

He raised the prospect of court action against those responsible for the spill, as Attorney General Eric Holder visited the Gulf to assess legal options.

"If the laws on our books are insufficient to prevent such a spill, the laws must change," Obama said, in a statement in the White House Rose Garden, lashing what he said was lax regulation of the offshore oil industry.

"If oversight was inadequate to enforce these laws, oversight has to be reformed.

"If our laws were broken leading to this death and destruction, my solemn pledge is that we will bring those responsible to justice on behalf of the victims of this catastrophe and the people of the Gulf region."