The death of Harambe the gorilla has been given six times more coverage on major US TV networks than the Coptic Christians beheaded by ISIS last year, new research has shown.

According to conservative blog NewsBusters, a website set up to "provide the immediate exposure of national media bias, unfairness, inaccuracy, and occasional idiocy", ABC, CBS and NBC have dedicated 1 hour, 28 minutes and 17 seconds of news coverage to Harambe since he was shot dead on May 28.

In contrast, just 14 minutes and 30 seconds have been spent on the 21 Egyptian Christians murdered by ISIS in Libya since February 2015.

NewsBusters branded this disparity "the very definition of absurdity", and accused the major networks of "routinely prioritis[ing] animal life over human life".

Harambe was shot by zoo staff after a three-year-old boy climbed into his enclosure at the Cincinnati Zoo and Botanical Garden last month.

The incident triggered significant criticism and a police investigation into the boy's family. The zoo has defended its decision to shoot Harambe.

The video of the Coptic Christians being beheaded was released on February 15 last year.

It showed black-clad ISIS militants marching the Christians along a beach in Libya before killing them. The last words of some of those murdered were "Lord Jesus Christ".

The five-minute video was titled: "A message signed with blood to the nation of the cross" and the men identified as "people of the cross, the followers of the hostile Egyptian Church."