New Zealand's biggest university has exposed its own students for selling old exam scripts online - a business a high-ranking staff member claims undermines academic integrity.

The website buys exam scripts from the past two years that scored more than 85 per cent for $25.

It then sells them for $5 to students in a move it says takes "the guesswork out of studying".

University of Auckland Deputy vice-chancellor Raewyn Dalziel sent an email to staff yesterday warning them to take the circulation of old exam scripts into account when preparing exam papers.

"I want to express my own profound disappointment and concern that students at the university are prepared to undermine the standards of academic integrity and the independence of thought that we strive to promote," she wrote.

When the website went live last month, it was initially advertised as "a new service launched ... at the University of Auckland".

But the owners retracted the statement after being approached by the university, Ms Dalziel wrote.

"The website is run by students at the university but has no connection with the university and it appears we cannot prevent the activity."

Students said the trading allowed students to share information but was not equitable. "Some people can afford it, some can't," said one.

The website said trading exam scripts was both legal and ethical.

"Exam scripts are the intellectual property of the students who sit exams, and just like any other commodity, it is perfectly acceptable to buy or sell them," it reads.

"All of the exam scripts on this website have been legally obtained by high-achieving students who have sold them. These students have sold us their scripts for a variety of reasons; some want the money, others want to help fellow students succeed in their tertiary studies."

In a section on the website about plagiarism, it said students should not download exam scripts "steal their ideas or find a model answer".

It said "to be on the safe side" students should cite sources for any assignment - including bought exam scripts - as completely as possible.

One of the website owners is understood to be graduate Bowen Pan, who was involved in setting up a website last year as a forum for students to rate university courses. He did not return Weekend Herald calls yesterday.