Significant and persistent quality problems centred on foreign students could see an entire class of qualification abolished.
The Qualifications Authority (NZQA) is considering the future of level 7 diplomas, one-year qualifications that sit at the same level of the Qualifications Framework as a bachelor's degree.
Consultation papers highlighted problems associated with the rapid proliferation of the diplomas as a qualification favoured by foreign students.
"The main issue associated with this qualification type is that there are some persistent and on-going quality concerns," an NZQA consultation paper said.
"Whilst there appears to be a strong need for level 7 diplomas in some industries, some have recently been used as a fast track to residency for international students. This led to an increase in provision, and subsequent concerns about international students' English language proficiency."
Another document said: "Since external monitoring of level 7 diplomas commenced in 2016 a number of significant issues with English language testing and assessment practice have been identified."
However, the documents also noted that immigration rules changed in December last year and the authority had strengthened its monitoring activities.
NZQA acting deputy chief executive for quality assurance Eve McMahon said the authority was considering options including abolishing the diplomas altogether, or retaining them but changing monitoring requirements and reviewing each of the existing qualifications.
"The main thing with the level 7 diplomas is that they are not a degree qualification, but they sit at the same level as degree qualifications and part of our thinking was do we need both or do we just need degree level qualifications at level 7," she said.
Qualifications Authority figures showed in 2017 there were 2550 equivalent full-time students enrolled in the programmes, 1520 of whom were foreign students.
Executive general manager academic and provost at Manukau Institute of Technology, Martin Carroll, said changes to work visas and residence rules had reduced foreign student enrolments in level 7 diplomas.
He said the qualifications were aimed at skill shortage areas and they had value for domestic students too.
"So there is a reason for having the programme, it was not simply a fast-track to residency for international students as some people have claimed."
Professor Carroll said the level 7 diploma should be retained because students in vocational education and training should be able to find vocational qualifications at every level of the Qualifications Framework.
"We want to keep these smaller packages of learning, these certificates and diplomas, at every level of the framework so they don't need to disrupt their career for a period of three or four years in order to access higher levels of learning."
The chief executive of private tertiary institute, Aspire2, Clare Bradley said half of its first-time international students were enrolled in level 7 diplomas.
She said axing the qualifications would hurt enrolments and it would take time to divert future students into other courses.
"Turning it on its head would be quite complex and quite time-consuming and certainly expensive for providers to adjust. It means reorganising a lot of our messaging, for us that's in about 30 different markets, and re-educating our recruitment networks."
Ms Bradley said the option of studying for a year and then working in New Zealand was attractive for a lot of foreign students.
Since 2016 the Qualifications Authority had taken a more stringent approach to monitoring the programmes, and that had driven some providers out of business, she said.