In a remote part of the United States, a mysterious metal monolith found has - just as mysteriously - vanished.

Last week the structure, which is about 12 ft high, was found planted in the ground in a red rock cove in Utah, sparking immediate speculation about how it got there.

But the Land Management Bureau of Utah said today that it had been deleted.

"The bureau said on Facebook: "We have received reliable information that an unknown party has removed the illegally built structure, referred to as the 'monolith,' from the Bureau of Land Management (BLM) public land.

The arrangement that is called private property was not replaced by the BLM.

We are not investigating cases involving private property that is covered by the office of the local sheriff.

The framework has received international and national attention and we have received reports that it was withdrawn on the evening of 27 November by an individual or party.

State wildlife officials who helped count the bighorn sheep from a helicopter found the monolith.

"That's been about the strangest thing that I've come across out there in all my years of flying," pilot Bret Hutchings told local news channel KSL TV.

"We were kind of joking around that if one of us suddenly disappears, then the rest of us make a run for it, We were kind of joking around that if one of us disappears suddenly, then the rest of us make a run for it."

"We were, like, thinking is this something NASA stuck up there or something. Are they bouncing satellites off it or something?"

He said it seemed to have been man-made, maybe by "some new wave artist" or a "big fan" of the 2001 science fiction film: A Space Odyssey, referring to a film scene.

A metal monolith is uncovered in the desert by apes in the 1968 Stanley Kubrick classic.