Some nuns are "brilliant teachers" who are doing "fantastic jobs", shadow education secretary Tristram Hunt has said.
The Labour frontbencher was asked a number of times whether an unqualified nun could be a good teacher before making the comment.
Last week, he was forced to insist he meant "no offence" to nuns after being accused of making "arrogant and ignorant" comments about their teaching ability.
He came under fire after he clashed with journalist Cristina Odone on a TV show as she praised the education she received.
Ms Odone said some of the "most inspiring" teachers she had were ones who had not been through teacher training colleges, prompting Mr Hunt to say "these were all nuns, weren't they?".
Today on the BBC's The Andrew Marr Show, Mr Hunt said: "I'm sure there are brilliant teachers who are nuns who are doing fantastic jobs."
On Thursday's Question Time, Mr Hunt, who has opposed the use of unqualified teachers in classrooms, said: "I know about your religious schooling and there's a difference, I think, between a state education system having qualified teachers in the classroom."
Ms Odone said she had been to a Catholic school, a state school and a private school and "the best (teachers) did not come out of teacher training college".
Following the exchanges on the show, Ms Odone hit out at Mr Hunt.
Ms Odone, a former editor of the Catholic Herald, told the publication: "Tristram Hunt's comments on nuns last night were arrogant and ignorant. Why is it acceptable to denigrate anything Catholic but bleat tolerance about every other religion?
"To know he and Labour stand a chance at the next election makes me fear for the 7,000 brilliant faith schools in this country."
Mr Hunt responded to the row by posting a message on Twitter saying: "On BBC QT I was trying to make a generalised point about the use of unqualified teachers in schools. I obviously meant no offence to nuns."