The Communication Workers Union (CWU) handed the cash to Coatbridge, Chryston and Bellshill MP Hugh Gaffney while promoting an anti-racism conference.
Mr Gaffney apologised after he referred to a Chinese meal as a “c****y” and referred to Scotland’s national poet as “bent” while addressing a Burns Supper in Edinburgh last month.
He offered unreserved apologies to the LGBT and Chinese communities after the remarks were reported in a national newspaper.
Despite the apology receiving widespread coverage, the CWU made the donation two days later on February 9, according to the MP’s updated register of interests.
“We know the CWU are closely aligned to Richard Leonard, and now it transpires they have backed Hugh Gaffney to the tune of thousands of pounds just 48 hours after he made these deeply offensive remarks, adding insult to injury,” SNP minister Humza Yousaf told The Herald.
“How the CWU could sanction this support after he was exposed as a bigot is beyond belief, especially while they are talking up their own credentials in tackling racism.
“Perhaps in light of these fresh revelations the CWU might finally confirm whether Hugh Gaffney ever underwent diversity training in his previous role as a union rep.”
Mr Gaffney, a CWU member, has previously said he is on a unpaid five-year career break from the Royal Mail while an MP.
Scottish Labour leader Mr Leonard yesterday denied his party had a problem with racism after more accusations were levelled against shamed Dumfries and Galloway councillor Jim Dempster.
He said: “We have got no more of a problem with racism than Scottish society as a whole. I am impatient and angry that we are receiving complaints and they will need to be dealt with thoroughly and timeously. There will be zero tolerance of racism and Islamophonia inside the Scottish Labour party.”