Coast Guard chief Adm Thad Allen said the storm put back efforts to drill a relief well by seven to 10 days.

But he said the operation to plug the well by pumping mud through the cap that has stemmed the flow of oil could start in three to five days. Experts say the choppy seas will have broken up some of the slick.

The storm will also leave some beaches cleaner, said Jane Lubchenco of the National Oceanic and Atmospheric Administration.

The Development Driller 3 - a rig boring into the seabed to make the first of two relief wells - and other ships involved in the clean-up had stopped operating on July 23 in advance of the storm.

The first relief well's completion now looks possible by mid-August, said Adm Allen, unless storms cause further evacuations of the site.

He said that on July 23, crews could begin pouring heavy mud and cement through the mechanical cap - the first of two stages to create a permanent seal.

The relief tunnel, when it is completed, will then pump in more mud and cement.