The staff member, who spoke to the Herald on condition of anonymity, said, "New Zealand soon became a magnet for agents wanting to put through fraudulent students because they know we have stopped checking if supporting documents are fake.
"You don't find such levels of fraud with applications to the US, Canada or even Singapore, because these agents know it is much tougher for students to get through the processes that these countries have."
Tertiary Education Minister Steven Joyce said two independent Chinese agents were linked to all the cases, and "one or two" local Chinese staff employed to work for Immigration were being investigated.
In a letter to the Herald, another Immigration staff member alleged that student visa fraud had become widespread and was not limited to Beijing.
"The fraud ... also extends to Shanghai branch, Hong Kong, Dubai, Pretoria and Bangkok branch," the writer said.
"This is just the tip of an iceberg. Indian, Pakistani, Sri Lankan and Middle Eastern students are committing huge frauds taking full advantage of relaxed immigration rules."
The Government's plan is to increase the value of export education from $2.3 billion to $5 billion annually, but overall international student applications in the past 12 months have dropped from 102,000 to 91,000 - the lowest since 2006.
To make it easier for international students to enter the country, health-screening rules were also relaxed this month, leaving the onus on them to declare their state of health rather than undergo compulsory medical checks.
Last year, the biggest increases in international student numbers were from China, up 1621 people or 11 per cent, followed by India, up 1485 or 17 per cent, and Saudi Arabia, up 341 or 19 per cent.
Steve McGill, acting head of Immigration NZ, said: "Beijing branch amended their profiling of applications in July 2011; the low-risk profile was adjusted to include tertiary diplomas and degree-level qualifications in China."
This was because verification done on these qualifications had not raised any issues in the past, he said.
"There has been little change in the number of student visa approvals or the proportion of visa approvals since we changed our risk management strategy for student visa applications," Mr McGill added.
"It is not correct to say that staff were told to increase student visa approvals or increase student numbers from China."
VISA NUMBERS
Student visa applications drop:2007-08: 94,034 (89,587 approved)
* 2008-09: 101,780 (95,356)
* 2009-10: 99,524 (93,767)
* 2010-11: 101,934 (93,921)
* 2011-12: 91,435 (83,899)
* July 2011: Immigration NZ Beijing stopped verifying most academic qualifications gained in China.
* May 2012: 279 students with visas granted through Beijing found to have fake qualifications and bank statements.
(Source: Immigration New Zealand)