US Vice-President Joe Biden has joined other politicians and celebrities in supporting the victim in the Stanford University sexual assault case, after the attacker received a six-month jail sentence widely criticised as too lenient.

Many have denounced the sentence by Santa Clara County Judge Aaron Persky on former Stanford swimmer Brock Turner, 20, over the sexual assault of an unconscious woman in January 2015 as a “slap on the wrist”.

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The uproar over the sentence, fuelled partly by the anonymous victim’s statement detailing the assault in graphic terms, is part of the growing outrage about rape on US college campuses.

Mr Biden addressed the victim and her statement in an open letter to Buzzfeed News, saying he was “in awe of your courage for speaking out”.

“I do not know your name — but your words are forever seared on my soul. Words that should be required reading for men and women of all ages,” Mr Biden wrote.

“I am in awe of your courage for speaking out.” Photo: Getty.

“I am in awe of your courage for speaking out — for so clearly naming the wrongs that were done to you and so passionately asserting your equal claim to human dignity.”

“And I am filled with furious anger — both that this happened to you and that our culture is still so broken that you were ever put in the position of defending your own worth.”

Republican US Representative Ted Poe from Texas called for Judge Persky to be removed from office and demanded the sentence be overturned in favour of harsher punishment.

“The punishment for rape should be longer than a semester of college,” Mr Poe, a former judge, said in the House of Representatives.

On Wednesday, New York Mayor Bill de Blasio posted a live video to his Facebook page of several people, including his wife, Chirlane McCray, and actress Cynthia Nixon, reading the 12-page letter the victim read in court addressing her attacker.

The case has also struck a nerve internationally, with social media users in China protesting the sentence on the networking site Weibo by posting images of women holding signs with messages of indignation.

“It is rape when she’s unconscious,” one sign reads. “It is still rape when he is a good swimmer.”