Political leaders in the US-administered Northern Mariana Islands have publicly rebuffed attempts by Washington to persuade them to support a huge marine sanctuary in their waters.

A US official said during a visit to the western Pacific territory this week that President George Bush wanted to establish the Mariana Trench Marine National Monument before he leaves office in January.

Supporters of the 115,000 square mile (297,850 square kilometre) reserve said it would be an important part of Bush's legacy as he leaves office.

"To be as blunt as possible, we do not feel... that stealing our birthright to curry favour with posterity is appropriate," Northern Mariana leaders said in a joint letter published Thursday.

Northern Marianas Governor Benigno R. Fitial, the Senate president and the House of Representatives speaker wrote to Bush's senior advisor on environment and energy James Connaughton, who led a trip to the territory earlier this week to promote the sanctuary.

Local leaders oppose the reserve because they say it would remove resources from local control, banning fishing and any future mining in the area.

The sanctuary would surround the territory's uninhabited northern islands of Maug, Asuncion and Uracus, and include parts of the Mariana Trench, the deepest ocean waters in the world.

Connaughton told legislators on Monday the waters around the three islands were chosen because they have the "greatest marine diversity on the face of the earth and all (the) corals are intact."

But local politicians said they felt they were being railroaded into supporting the plan.

"We certainly do not appreciate the rush to judgment that necessarily must take place, and possibly has already taken place, to secure the designation prior to January 2009," the letter added.

"Even though this was ostensibly the beginning of discussions, many present were left with the feeling that the result was pre-ordained and the discussion was more pretense than substance."