Oxford University has apologised to David Lammy after retweeting a post labelling his criticism "bitter".
The original tweet, sent by a student, was in response to the Labour MP saying Oxford was "a bastion of white, middle class, southern privilege".
Mr Lammy asked if the tweet represented the university's official position - at which point a senior staff member apologised and took responsibility.
The row follows the university's report into its student population.
Oxford's director of public affairs, Ceri Thomas, said Mr Lammy's comments showed "no sign of bitterness" and there was "work to do" to improve diversity among students.
Hello @UniofOxford is it your official position that I am "bitter" just because I am prepared to criticise your institutional failings on access, FOI the data and publish it? This contradicts your press statements that say how determined you are to improve access. Which is right? pic.twitter.com/K9pkojAdJv— David Lammy (@DavidLammy) May 23, 2018
Hello @DavidLammy Apologies: it was my call to retweet our students including @liambeadle. But we agree with you that Oxford needs to do more and criticism of us is no sign of bitterness. There’s been progress, but work to do.— Ceri Thomas (@CeriThomas01) May 23, 2018
Mr Lammy's original remarks came as Oxford University data revealed eight of its 29 colleges included in the report accepted fewer than three black applicants in the past three years.
The university has a total of 38 colleges and permanent private halls.
The university said it was "not getting the right number of black people with the talent to apply".
Director of undergraduate admissions Dr Samina Khan told the BBC she was "pushing hard" on outreach activity to make sure those students felt welcome.
Mr Lammy told the BBC that Oxford was "failing badly".
The proportion of Oxford students identifying as black and minority ethnic was 18% in 2017, up from 14% in 2013. However, that figure still falls below the UK university average of 25%.
The most recent UK census showed 14% of the UK population identifies as black or minority ethnic.
Data in the university's report showed that, of the students that achieved three 'A' grades or higher in their A-levels nationwide, 20% identified as black and minority ethnic.
One college, Corpus Christi, which has around 350 students, admitted one black student resident in the UK in its 2015-2017 intakes.
Balliol college, which has around 680 students, admitted two black students over the same period, despite receiving 46 applications.
The number of admissions from state schools, during the same period, rose by 1%, from 57% to 58%.
The report also showed a divide between the north and south of the UK.
London and the South East made up 46.7% of UK applications between 2015 and 2017, (and 47.9% of students admitted) while the North East accounted for 2% (2.3% admitted).
Speaking to Radio 4's Today programme, Mr Lammy said the university had to explain why - having looked at the data - a person was twice as likely to get in if they were white, not black.
Mr Lammy previously accused the university of "social apartheid", after a Freedom of Information request by him revealed 10 out of 32 Oxford colleges did not award a place to any black British pupil with A-levels in 2015.
This prompted more than 100 MPs to write to Oxford and Cambridge urging the universities to recruit more students from disadvantaged and under-represented backgrounds.
Reacting to the latest figures, Mr Lammy said the problem was "self-perpetuating".
"If you're on the 20th floor of a tower block estate and you're getting straight A's, you apply, go for a difficult interview.. you don't get in, then none of the other kids apply the following year."
"It's very elitist, very, very white," student Taiwo Oyebola said. "For me, applying for Classics, I was very aware I'd be the only black person or one of a few people of colour."
"We have this joke in lectures, I go in and there's this group we call them the Eton row, because all the Eton boys sit there."
Joshua Tulloch of the Oxford African and Caribbean students society said his organisation was involved in targeting younger black students.
"We have a vast access infrastructure which targets students from as young as Year 9," he said.
"The university is supporting us in making sure that we are visible and people can see that they can succeed in Oxford."
Oxford has said it must do more to attract talent from all backgrounds.
"We want a diverse university," Dr Samina Khan told Radio 4.
The university has agreed to a scheme which would fund the interview travel fees of applicants from disadvantaged backgrounds.
It said it is doubling its spring and summer schools, which work with students from under-represented backgrounds.