A US federal judge ruled in favour of the Ringling Bros and Barnum & Bailey Circus in a case brought by animal rights activists who accused the circus of abusing elephants.

US District Court Judge Emmet Sullivan said former Ringling employee Tom Rider and the Animal Protection Institute did not have legal standing to sue the circus, owned by Feld Entertainment Inc.

Mr Rider and the animal protection group brought the lawsuit under the Endangered Species Act.

During the six-week trial in February and March of this year, the attorney for the animal rights groups asked the judge to stop the circus from harming the elephants during performances and punishing them for bad behaviour.

They alleged that the use of bullhooks and prolonged chaining violated US federal law.

Feld Entertainment argued that the animals are not hurt and that the instruments are necessary to keep the elephants under control and protect public safety.

At the time, the judge expressed some reluctance to police circus methods and asked how the prods and chains are different from spurs used on horses and whips with tigers.

Ringling Bros said during the trial it cannot have the Asian elephants without these instruments because there is no other proven way to keep the animals under control and protect their trainers and the viewing public.

Feld's attorneys said their elephants are healthy, alert and well-cared for, including those that travel with the show and those that live at the company's 200-acre conservatory in Florida.