An immigration adviser says new figures are at odds with previous assurances that Indian students and graduates are not being targeted by immigration officials.
Immigration New Zealand says there has been no change to its assessments.
Figures show 14 percent of Indian applicants were rejected last year for the employer-assisted work visa, compared to 4 percent for Chinese applicants.
Arunima Dhingra, a director of Aims Global, said the number of post-study work visas were being "slammed" and genuine Indian applicants were suffering.
"They have gone through the right channels all throughout and yes there is tightening which is not said, not accepted, not disclosed and yet the numbers kind of show it.
"Because every time we've asked immigration 'what's happening? Are you singling them out? Is there a different way of processing applications for Indian nationals?' We've always had 'no, it's never that.'"
In the essential skills work visa category, 19 percent of declines were for Indian applicants.
Of those in the country unlawfully and appeal 922 of 2541 Indian applicants were approved, compared to 828 of 1232 Chinese applicants and 239 of 310 British immigrants.
There was a benefit of the doubt given to their European clients which was not extended to Indian applicants, Ms Dhingra said.
"I think the overall picture that's been painted is that, you know, 'Indian nationality applications, let's just go hard'," Ms Dhingra said.
"If immigration is doing that they need to stand up and explain that's what it is rather than say 'nah, nothing's changed', because clearly something has."
Temporary visa applications can take months
Applications for some temporary visas were often taking four months, she said.
"The figures show clearly that Indian students moving to work visas are not just targeted, but the numbers are being slammed. And in doing this extreme tightening, the genuine Indian students also end up paying and losing their entire career."
Harshmeer Kaur, who set up NZ Student Association Facebook page, said it was hard for international graduates now and there were long delays in visas being processed.
It used to take 10-15 days for a temporary visa, but it was now taking months, she said.
"I haven't heard anything from other nationalities, but a lot of Indian students are returning home because either their visa is being declined or they don't have the opportunity to present themselves properly.
"They are declining a lot of visas I don't know why. They're not even asking proper questions of the employer and they're making so many mistakes.
"Some of the visa [applications] are sent to China as well and I don't know what the immigration people over there do," Ms Kaur said.
"Because ... of all this happening, very talented people ... I have seen go back who would have been a great thing for New Zealand. But no, they've gone back now, gone back to India and doing good for India."
She believed immigration officers may be viewing Indian applications differently because of the previous concerns over lower quality education providers and fraudulent Indian agents.
Each application assessed on merits - INZ
An Immigration New Zealand (INZ) manager, Michael Carley, said each application it received was assessed on its merits and in-line with the relevant instructions.
"There can be a variety of reasons for why an application is declined - immigration officers are required to consider applications under the relevant policy, which includes health and character," he said.
But Ms Dhingra is unconvinced.
"The numbers leave INZ no room to hide behind 'no changed policies' anymore as the numbers speak loudest."
Immigration New Zealand documents released under the Official Information Act include discussion of half of private training establishment students coming from "migration-motivated markets", although it has redacted which countries these refer to.
Another report points out the risk immigration changes could be perceived as targeting particular countries, which could have the potential for impact New Zealand's foreign relations.
Officials from the Ministry for Business, Innovation and Employment and the Ministry of Foreign Affairs and Trade met with foreign missions including China, India and the Philippines to assure them that the changes were not targeted at any nationality or at international students.
A review of post-study work rights is underway.