As BP continues work to plug the huge Gulf of Mexico oil spill, US President Barack Obama has confirmed a six-month extension of the moratorium on permits for new deepwater oil drilling.
Earlier, his administration announced the resignation of the head of the Minerals Management Service (MMS), which oversees offshore drilling operations.
Mr Obama said the MMS had been plagued by corruption for years. Many US lawmakers and environmental groups had blamed the agency for lax regulation of offshore drilling rigs and production platforms.
BP's managing director Robert Dudley said a complex "top kill" operation started on Wednesday to try to halt the seabed well's flow by pumping heavy drilling fluids into it was making progress, but it was too early to say whether it had been successful.
The leak began after an explosion on the Deepwater Horizon drilling rig on 20 April, killing 11 workers. The rig sank two days later.