One of Hollywood's best known actresses has appealed for public help in stopping the execution of a man she says is "clearly innocent".

Sarandon said next month's scheduled execution in Oklahoma shows everything that is wrong with the death penalty in America.

She also described the governor of Oklahoma as a "horrible person" for refusing to intervene.

Sarandon won an Oscar for her portrayal of anti-capital punishment campaigner Sister Helen Prejean in the 1995 film 'Dead Man Walking.'

Richard Glossip is scheduled to die by lethal injection on September 16th, but has always maintained he is innocent.

He was convicted of murder after the man who confessed to the killing claimed that Glossip had hired him to do it. In return for his testimony, Justin Sneed was given a prison sentence, whereas Glossip was sentenced to death.

He has been on death row for 17 years but has exhausted all appeals, including to the US Supreme Court.

Sarandon told Sky News: "Richard's case is so typical. Bad representation; two trials that were ridiculous, no physical evidence. He's put there by a snitch who actually did kill the person, and then the snitch has life and this guy is being put to death on the 16th."

"Once a mistake has been made within a judicial system, people just do not want to admit that mistake has been made and it becomes impossible to readdress them. And the only thing now that is going to give him a chance to survive is public opinion - is public embarrassment."

The actress is urging people to write to Oklahoma Governor Mary Fallin - asking her to intervene and grant a stay of execution. So far she has refused to do so.

"The governor of Oklahoma is just a horrible person, and a woman, so it's even more discouraging," Sarandon said.

"Being tough on crime means being for the death penalty, somehow that got established, so when you're attempting to protect your political career, you can't ever look at the complexities if you want to keep your mantra going."

"It's never because of some consciousness-raising that these things change, it's because of some kind of embarrassment. And so this is where public opinion can make a difference."

"This is where having letters sent to the governor can make a difference, because then they understand. He's (Glossip) a perfect example of what's wrong with the death penalty, and so of course, I'm hoping that some kind of exposure will give him the opportunity to maybe get his sentence at least commuted, because he's clearly innocent, and on top of that the guy who actually killed the person is in a minimum security prison for the rest of his life."

The movie 'Dead Man Walking' was based on a book by Sister Helen Prejean who works with death row prisoners. She has visited Glossip in prison and has agreed to be his spiritual advisor in the hours before his execution.