A bid to free five elephants from a Colorado zoo has been rejected after a court ruled elephants are not people.

An animal rights group argued Missy, Kimba, Lucky, LouLou and Jambo were effectively imprisoned at the zoo, and had filed to have them moved to an elephant sanctuary.

It tried to bring a habeas corpus claim on behalf of the animals - a legal process which allows a person to challenge their detention in court.

The Colorado Supreme Court said the matter boiled down to "whether an elephant is a person" and therefore had the same liberty rights as a human - ultimately deciding that they did not.

It ruled 6-0 in favour of a previous district court decision that said the state's habeas corpus process "only applies to persons, and not to nonhuman animals".

This was true "no matter how cognitively, psychologically, or socially sophisticated they may be," State Supreme Court Justice Maria Berkenkotter added in her ruling, external.

While she said the five elderly African elephants were "majestic," the court ruled the claim could not be brought "because an elephant is not a person".