Channel 4 has defended the right of comedians to make jokes which "push boundaries" after reality TV star Katie Price complained about Frankie Boyle.
Price said Boyle's joke about her disabled son Harvey was "vile" and she criticised Channel 4 for showing it again in a repeat.
Media regulator Ofcom has launched an investigation into the complaint.
The charity Mencap described Boyle's joke as a "disgusting" attack on a disabled child.
Price said: "By repeating Frankie Boyle's show, Channel 4 are embracing and exploiting discrimination."
But Head of Comedy, C4, Shane Allen said: "We are aware that Frankie Boyle's comedy can be very challenging which is why we have gone to careful lengths in scrutinising the material editorially, in scheduling the series appropriately and by giving clear and strong warnings into each of the programmes.
"We think that it is important that a space on terrestrial TV exists for comedy that takes risks and pushes boundaries and we stand by our original decision to broadcast the programme."
Price responded by saying: "They are saying it is ok to ridicule people - even children - for disability in a way they would not dare over race or sexual orientation.
"The people who control the channel are endorsing this behaviour and it is disgusting. Even the fact that Ofcom are investigating the first broadcast has not made them divert from this path.
"This issue is not about me, other than Harvey is my son. This issue is about discrimination."
She added: "By broadcasting these vile sexual comments about Harvey, and then insisting on repeating them, Channel Four are trying to take us back to an era when discrimination was accepted.
"They mustn't be allowed to get away with it."
She was supported by Mencap's campaigns manager, Esther Foreman, who said: "It is disgusting that Frankie Boyle has chosen to target a child with a disability with these so-called jokes.
"Ignorant views like this help to fuel the verbal and physical abuse that people with a disability, and their families, are regularly subjected to. Comedy like this takes us back to the dark ages."
She said: "How can we eradicate negative stereotypes and expect the general public to treat people with a disability with the respect they deserve when such vile jokes are aired on national television?
"How can Channel 4 justify broadcasting this? The answers they have given so far are not satisfactory in the slightest?"
Boyle has become known for his controversial stand-up routines.
In April he had an on-stage argument with the mother of a child with Down's syndrome after making fun of the condition.
In 2009, the BBC Trust said satirical gameshow Mock The Week breached editorial guidelines over a Boyle joke about the appearance of Olympic swimmer Rebecca Adlington.
Ofcom said a judgement made over Boyle's comments would not be determined until the new year.