The smooth, tall structure was found during a helicopter survey of bighorn sheep in southeastern Utah, officials said on Monday.

A crew from the Utah Department of Public Safety and Division of Wildlife Resources spotted the gleaming object from the air on November 18 and landed to check it out during a break from their work.

They found the three-sided stainless-steel object is about as tall as two men put together.

But they discovered no clues about who might have driven it into the ground among the undulating red rocks or why.

"This thing is not from another world," said Nick Street of the Utah Highway Patrol, part of the Department of Public Safety.

Still, it's clear that it took some planning and work to construct the 3-to-4-metre monolith and embed it in the rock.

The exact location is so remote that officials are not revealing it publicly, worried that people might get lost or stranded trying to find it and need to be rescued.

The monolith evokes the one that appears in the Stanley Kubrick movie 2001: A Space Odyssey.

Because it's on federal US public land, it's illegal to place art objects without authorisation.

Bureau of Land Management officials are investigating how long it's been there, who might have created it and whether to remove it.

Australian Associated Press