George Bush has designated 200,000 square miles of the Pacific as conservation areas in a bid to re-write his conservation reputation before he leaves office.

Mr Bush, who has steadfastly refused to impose statutory limits on carbon dioxide emissions to combat global warming, became the leader who has protected more of the oceans than anyone else in the world.

The areas protected, with the active intervention of the First Lady, Laura Bush, include pristine coral reefs, the habitat of vanishing marine species, and the deepest place on Earth, the Mariana Trench.

Mrs Bush is understood to have headed-off determined opposition from the vice-president, Dick Cheney, as well as business leaders in the Mariana islands who had lobbied on behalf of the fishing industry and oil and gas exploration firms.

The conservation areas will ban commercial fishing, mining and energy exploration within the protected areas.

Recreational fishing will be allowed only with a permit and the number of these will be limited.

However they will fall short of meeting scientists recommendation for a protected zone stretching out 200 miles to the edge of US waters. Instead, the protected areas will extend only 50 miles.

James Connaughton, head of the White House Council on Environmental Quality, said:

These locations are truly among the last pristine areas in the marine environment on Earth.”

Joshua Reichert, managing director of the Pew Environment Group, said: “This is very, very big. Basically, in the last several years, it’s on a par with what we have been able to achieve on land in the last 100 years.

We and others in the environmental community have been at odds with this administration on lots of things, but if one looks at this one event it is a significant conservation event.”

Mr Bush created what was then the world’s largest marine protected area in the Pacific in 2006, using a law originally intended for the protection of antiquities.

Some 140,000 square miles in the northwestern Hawaiian islands became the Papahanaumokuakea national monument.

The new Marianas marine national monument will protect the Mariana Trench - six miles deep and five times the size of the Grand Canyon - and 21 active volcanoes.

The area is home to a diverse fish population and the Micronesian megapode, a bird which uses the heat from volcanic vents to hatch its eggs.

The Pacific remote islands national monument will cover a series of coral reefs and atolls.