A tertiary institute is describing visa delays for hundreds of prospective international students as a crisis.

Aspire2 International says it's been waiting more than a month for most of their 500 pending student visas to be approved, and many have missed the cutoff date for this semester.

Immigration moved all visa processing offshore last year, at a time when applications were on the rise.

Aspire 2 CEO Clare Bradley told Mike Hosking the delays are impacting New Zealand's reputation as a study destination.

"Education New Zealand has released forty pages of briefing to the Minister about the impact this is having on revenue."

She says they may have missed out on $6 million in fees this semester.

"We may get it further down the track, we may not, as a the sloweness of the visa process is having a detrimental effect on New Zealand's attractiveness as a study destination."

New Zealand Shores Director Allan Crome says some of the students he works with are making the cut-off but only by days.

"The visas are getting approved pretty much at the last minute. It might be the week before the actual study commences. If you look at any of us moving overseas and you leave in a matter of days, it's quite unrealistic in that sense."

He says many students are paying upfront for their courses, and getting ready to quit their jobs, without knowing if they'll have a place to study.

"Transferring anywhere between $20,000 to $40,000 for a 12 month tuition, so they've embedded their finances here essentially, and then having to delay their migration to New Zealand as a result."

Bradley says the students may be able to come for the next intake, but it's already having an impact on their bottom line.

"We are reducing our premises where we can. It is fair to say that we have not replaced staff directly as a result of this."

She is worried the delays will have a long-term impact on the number of students who want to come here for study.

Bradley told Mike Hosking people won't come here if they can't see certainty, care and attention. 

"A study destination is a high trust area, as not only as you travelling thousands of miles to come to New Zealand, but you are investing tens of thousands of dollars."