The BBC denied it had used double standards in dealing with the Strictly Come Dancing race row, by keeping Anton Du Beke on despite axing Carol Thatcher over a similar incident.
The corporation is under pressure to sack Du Beke after it was revealed he described actress Laila Rouass as a "Paki".
Hope Not Hate, the anti-racism campaign, said Du Beke should be axed from the popular show for his remark to the former Footballers' Wives star.
The call came after Thatcher, daughter of former prime minister Baroness Thatcher, was sacked earlier this year from the BBC's The One Show after referring to a tennis player as a "golliwog".
A spokesman for Hope Not Hate, a campaign run by the anti-fascist magazine Searchlight, said: "If calling someone a Paki is not racist behaviour then what is? Quite simply the programme has to ask itself, is it going to condone racism on its show or is it going to deal with it quickly and decisively?
"The BBC took a clear line on the Carol Thatcher golliwog comment. If anything this comment is even more offensive."
But a spokesman for the BBC said Du Beke had offered an unreserved apology, whereas Thatcher had apologised but maintained it was a joke.
The spokesman said her apology was not unconditional, despite explanations that the term was offensive.
He said: "Anton understands that it's offensive and has unconditionally apologised."
Du Beke used the insult a fortnight ago during rehearsals after Rouass, his celebrity dance partner, had used a spray tan, the News of the World said.
The 38-year-old actress was reportedly "gobsmacked" by the comment, which was overheard by several members of the Strictly team.
He admitted the term was used "in jest", but denied he was a racist and apologised for "any offence".
Du Beke said: "I must say immediately and categorically that I am not a racist and that I do not use racist language.
"During the course of rehearsals Laila and I have exchanged a great deal of banter entirely in jest, and two weeks ago there was an occasion when this term was used between the two of us.
"There was no racist intent whatsoever but I accept that it is a term which causes offence and I regret my use of it, which was done without thought or consideration of how others would react.
"I apologise unreservedly for any offence my actions might have caused."
Rouass, who has an Indian mother and Moroccan father, has since accepted Du Beke's apology.
She said: "It was a situation which happened that we have moved on from and I accept his apology.
"I'm really enjoying the show and dancing with Anton and hope we can go as far as possible in the competition."
The BBC confirmed speculation that Amy Winehouse will sing backing vocals for her 13-year-old god-daughter Dionne Bromfield in a live performance on this Saturday's show.
The Grammy winner will provide backing vocals as Dionne performs her single Mama Said, taken from the forthcoming album Introducing Dionne Bromfield.
This weekend also sees another much-awaited comeback - as Robbie Williams performs his new single Bodies on The X Factor on Sunday.
The former Take That star's appearance on the show will mark the first time he has performed in the UK since 2006.
BBC1's Strictly starts at 7pm and ends at 9.15pm, while The X Factor, which kicks off its live stages this weekend, is running a two-hour show on ITV1 from 8pm on Saturday.
Winehouse was quoted in the Radio Times as saying of Dionne, who is signed to the Rehab singer's own label, Lioness Records: "She's so much better than I was at her age. I'm so proud. She's my number one."
The troubled star, 26, made her return to live performing in Britain in August after an eight-month stay in the Caribbean.
She appeared on stage with ska band The Specials at the V Festival in Chelmsford.
Winehouse has struggled with drink and drug problems in recent years and was divorced by her estranged husband Blake Fielder-Civil in July on grounds of adultery.
Dionne said in a statement: "Amy and I both love Strictly Come Dancing.
"I watch it every single Saturday, so it was brilliant to find out I'll be on TV for the first time singing on one of my favourite shows."
Mark Linsey, controller of entertainment commissioning, added: "We are delighted to showcase the television debut of Dionne Bromfield on Strictly Come Dancing.
"Dionne is an exceptional new talent and it will be an extra special event for our viewers to see her perform alongside Amy Winehouse, an artist we have been looking to book on the show for some time."