A breast-feeding mother has been banned from entering the University of Auckland's childcare centre to feed her 16-month-old baby.

The ban was issued on the same day the woman, Shu Chin Ma, asked university staff how they were progressing with a formal complaint she had made against creche staff.

She has had two boys with the creche daily for three years, but the university's director of administration, Adrienne Cleland, emailed Ma, a university faculty member, at 4.20pm on Wednesday to inform her that she needed to "arrange for another caregiver" to do drop-offs and pick-ups.

The message arrived just minutes before Ma, a pharmacometrics research fellow at the Medical Faculty, was due to collect her baby. She had already removed her 3-year-old from their care.

Ma said she had spoken to the centre's supervisor earlier that day about what she felt was a lack of progress on a formal complaint made the previous week.

She had alleged that lunch-box food was not given to one son, and that a senior staff member had not handled complaints well.

"My young son was forced to drink from a bottle ... either someone else's breast milk or formula. My older son was told that he could not drink juice because it was a fizzy drink and that dried strawberries were candies," Ma said.

She said she had raised her voice, but there were no threats or swearing, yet she had been banned.

Cleland said Ma had caused "great upset and fears for personal safety".

"The information provided to me so far causes me to be very concerned for the emotional and physical safety of the children, parents and staff at the centre," she said.

"I realise it was a difficult thing for a breast-feeding mother. There were other options, such as taking the child across the road to her.

"The complaints were of a serious enough cause for concern."

Two investigations are now underway - one into the allegations of staff withholding food and one into Ma's behaviour.

Ma told the Herald on Sunday the problems started four months ago, but came to a head over the past fortnight.

"I have had security called in and been forbidden to go and see my young son during the daytime. The situation is terrible," she said.