A top adviser to President Barack Obama says no new oil drilling will be authorized until authorities learn what caused the explosion of the rig Deepwater Horizon.

David Axelrod also defended the administration's response to the April 20 accident, saying "we had the Coast Guard in almost immediately."

He deflected comparisons with the government's slow response to Hurricane Katrina in 2005, telling ABC's "Good Morning America" that such speculation "is always the case in Washington whenever something like this happens."

Obama recently lifted a drilling moratorium for many offshore areas, including the Atlantic and Gulf areas. But Axelrod said Friday "no additional drilling has been authorized and none will until we find out what has happened here."