A former killer whale trainer at SeaWorld has spoken out about conditions at the attraction, after the deaths of three orcas there this year.

Last week, Kasatka became the third killer whale at the Californian theme park to die. She was put to sleep following lengthy treatment for lung disease, according to SeaWorld.

The orca was 41 years old, making her the oldest killer whale at SeaWorld in San Diego. According to wildlife charity Born Free, the majority of the animals kept in captivity do not live beyond 25 years.

And former trainer John Hargrove claimed Kasatka’s death was caused by bacterial infections, because the creatures' immune system becomes impaired due to being given antibiotics for years.

“By the end she had lesions on her face, like an Aids patient," he told The Mail on Sunday.

"SeaWorld will never release the autopsy but the internal wounds will be far worse.”

He added: “I have to speak out because if it stops just one person paying to go to a park where orcas are tortured to perform circus tricks, then Kasatka's death won't have been in vain.”

Kasatka appeared in the award-winning film Blackfish, in which trainer Ken Peters nearly drowned after being dragged to the bottom of a tank by the 5,000-pound orca.

In October, three-month-old killer whale Kyara was also put down, with pneumonia given as the cause of death. She was the last of the now defunct captive breeding programme.

Tilikum died of a persistent bacterial infection in January and was believed to be about 36 years old. The male orca was involved in the death of trainer Dawn Brancheau in 2010 after Tilikum grabbed her pony tail and pulled her into the water.

In Mr Hargrove’s account of Brancheau’s death, she “had her scalp ripped off. Her spinal cord was severed. Her left arm was ripped off.”

SeaWorld's killer whales Show all 10 1 /10 SeaWorld's killer whales SeaWorld's killer whales Visitors are greeted by an Orca killer whale as they attend a show featuring the whales during a visit to the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales A trainer shows the crowd a killer whale during a show at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales An Orca killer whale is seen underwater at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Visitors get a close-up view of an Orca killer whale during a visit to the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Trainers have Orca killer whales perform for the crowd during a show at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Trainers have Orca killer whales perform for the crowd during a show at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Trainers have Orca killer whales perform for the crowd during a show at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Trainers have Orca killer whales perform for the crowd during a show at the animal theme park SeaWorld in San Diego, California March 19, 2014. A California lawmaker introduced a bill to ban live performances and captive breeding of killer whales in the state, a measure that would force the SeaWorld San Diego marine theme park to end is popular "Shamu" shows. Mike Blake/Reuters SeaWorld's killer whales Tillikum, a killer whale at SeaWorld amusement park, performs during the show "Believe" in Orlando, September 3, 2009. A killer whale at the SeaWorld amusement park in central Florida killed a trainer on February 24, 2010, police and company executives said. According to the Orlando Sentinel the orca involved in the incident, named Tillikum but popularly known as "Tilly," has a controversial past. Mathieu Belanger/Reuters SeaWorld's killer whales An unidentified trainer works with a killer whale during the "Believe" show at Sea World in Orlando, Florida, in this photograph taken on February 14, 2010. A killer whale at the SeaWorld amusement park in central Florida killed a trainer on February 24, 2010, police and company executives said. Picture taken February 14. Richard Baum/Reuters

SeaWorld issued a statement denying the theme park was harmful for killer whales and for trainers working with the animals.

The Independent has contacted SeaWorld for comment.

The theme park, which Mr Hargove calls “a disgrace to humanity”, will be phasing out the killer whale performances by 2019 after public sentiment turned against the orca performing antics such as jumping through hoops for entertainment.