President Trump has announced plans to slash the size of two US national parks, provoking fury from environmentalists, native american tribes and conservationists.

Mr Trump called for the 1.3 million acre Bears Ears National Monument to be cut back to 228,784 acres split into two separate areas.

He also called for Grand Staircase Escalante Monument to be slashed by half to just under one million acres and split into three areas.

Both parks, or monuments as they are called, are in the dramatic Southern Utah red rock country.

The changes will make way for oil and gas drilling, mining and other resource extraction activities in the beauty spot.

Unlike national parks that can only be created by an act of Congress, national monuments can be designated unilaterally by presidents under the century-old Antiquities Act, a law meant to protect sacred sites, artifacts and historical objects.

Mr Trump travelled to Salt Lake City to make the announcement at a rally on Monday. A protest is being organised by the Southern Utah Wilderness Alliance and on Saturday, thousands of demonstrators holding signs with messages like "Protect Wild Utah" converged on the steps of the Utah State Capitol.