David Cameron is under pressure to give up £1.5 million in donations from businessman Dave Whelan amid allegations of racist comments by the Wigan Athletic chairman.
Labour backbencher Karl Turner has written to the Prime Minister urging him to condemn the remarks and hand the money to charity.
Mr Whelan became emboiled in the row as he tried to defend his decision to employ Malky Mackay as the club's manager, despite a Football Association investigation into claims he sent anti-semitic messages to a friend while in charge at Cardiff.
The 77-year-old former JJB Sport boss is said to have told the Guardian: "The Jews don't like losing money ... I think Jewish people do chase money more than everybody else".
He also reportedly argued there was "nothing bad" about referring to Chinese people as "Chinks".
Mr Whelan has apologised for causing offence, and suggested he had been misquoted.
But in a letter to Mr Cameron, Mr Turner said: "David Whelan is a significant donor to the Conservative Party, and has donated £1.5 million since 2007.
"His most recent donation of £100,000 was received by the Conservative Party on the August 2 2014.
"Given his status as a significant contributor to your re-election efforts you must now make it clear if you personally condone or condemn these comments.
"I hope that you agree with me that these anti-Semitic and racist comments have no place in modern British society, and as such I hope that you also agree with me that you must now give up any money that you have received from Mr Whelan and consider which charitable groups would be better recipients of it.
"Failure to act swiftly in this matter will show a lack of leadership. It will not be possible for you to simultaneously condemn offensive remarks while accepting large sums of money from those responsible for them."
Jenny Wong, director of the Manchester Chinese Centre, has said that Dave Whelan's comments about Chinese people were 'not very nice' and that he should have been 'more considerate' about his choice of words.
Cardiff City owner Vincent Tan has hit out at Wigan owner Dave Whelan and manager Malky Mackay calling them both 'racists'.
The Malaysian businessman was speaking after Whelan gave an interview to the Guardian where he said 'Jews chase money more than anybody else' and said it was acceptable to refer to Chinese person as a 'chink'.
Tan sacked Mackay, who was appointed Wigan manager on Wednesday, as Cardiff boss last year.
It was later revealed that Mackay had exchanged offensive text messages with a former colleague.
Mackay has apologised for his involvement in the texts and denied he had prejudices, saying: "I'm no racist. I'm no sexist. I'm no homophobe. I'm no anti-Semite."
"I think he insulted the dignity of all Jewish people. I think he insulted the dignity of Chinese," Tan told the BBC.
"I'm so disappointed the chairman of Wigan, a big club, is also a racist. This is a racist chairman hiring a racist manager.
"I hope that stops at two racists in Wigan, not snowballing to 2,000 or 20,000 racists in Wigan."
Whelan has since apologised for the comments, saying he did not mean to cause offence.
The Wigan said earlier: "I apologise on my behalf and on behalf of the club. We do not ever want to insult any nation or any person in the world."
The Football Association have released a statement in light of comments made by Wigan chairman Dave Whelan:
“We are very concerned to read about the comments that have been attributed to Dave Whelan. We take all forms of discrimination seriously.
“As with all such cases, this will be dealt with as a priority. The investigation is already under way and The FA's Governance Division have written to Mr. Whelan. He has three working days to respond.”
Labour MP Ivan Lewis has called for Wigan chairman Dave Whelan to stand down, after he made comments about Jewish and Chinese people that have been deemed offensive.
The Bury South MP said the Football Association needs to take the "toughest possible action" against Whelan, after what Lewis called his 'abhorrent' comments.
Wigan Athletic have received another blow after drinks company iPro Sport ended their sponsorship deal with the Championship club.Read the full story ›
Wigan owner Dave Whelan has apologised for any offence and defended his position after being accused of anti-Semitism.Read the full story ›
Wigan FC Chairman Dave Whelan is being accused of being racist and anti- semetic while defending the appointment of Malky Mackay as new manager, according to an interview he's given to a national newspaper.
Mackay was unveiled as Latics new boss yesterday despite an ongoing FA investigation into racist, sexist and homophobic text messages he sent during his time as Cardiff manager.
Meanwhile, kitchen firm Premier Range, has now announced ending it is shirt sponsorship with the club because it feels its position is "untenable".
Video courtesy of Wigan Athletic Football Club website.
Malky Mackay has taken his first training session as Wigan manager.
He was unveiled as the club's new boss yesterday.
Former Wigan manager Roberto Martinez has wished his old club and their new manager success.
Malky Mackay was unveiled as Wigan's new boss yesterday - despite being investigated by the FA for allegedly sending a series of sexist, racist, and homophobic texts.
Speaking today, Martinez told the press 'everyone makes mistakes'.