Some of the vessels working on BP's blown-out underwater well were returning to the oil spill site as storm Bonnie eased Saturday, a U.S. commander said.

Most of the BP 10 to 15 vessels that were at the site started to return Saturday afternoon and will be back on the scene within 24 hours, Admiral Thad Allen, the U.S. commander for the spill, told reporters.

The U.S. government has ordered the evacuation of ships and personnel working in the Gulf of Mexico oil spill site due to the approaching tropical storm Bonnie.

A rig drilling a relief well intended to kill the leak permanently was also en route to return to the site, BP spokeswoman Jessie Baker said. The rig stopped operations on Friday in advance of the storm.

The rig, together with the drill ship Discoverer Enterprise, was expected to be on site by Saturday night, according to BP.

The U.S. National Hurricane Center said Bonnie was less likely to redevelop into a tropical storm and could degenerate into an area of low pressure later on Saturday.