Education Minister Hekia Parata says a mailing error which led to 455 NCEA exam papers being sent to the wrong students was a "regrettable mistake".
She told Parliament this afternoon that the New Zealand Qualifications Authority (NZQA) had apologised for the blunder.
"In the context of our 161,000 students having their 1.1 million scripts returned - something which only New Zealand does - there was a mailing error affecting the return of scripts to 455 students.
"While it is a regrettable mistake, and it is the first time there has been a sorting and mailing error of this kind, the chief executive of NZQA has apologised and assured me that future quality checks have been put in place."
Ms Parata knew about the lost papers in January but was not aware of the scope of the mistake until yesterday [MON].
Asked by Labour education spokesman Chris Hipkins why she did not act sooner, Ms Parata said: "Because the focus has been on fixing it."
Around half of the exam papers were recovered immediately, and NZQA was working on recovering another 180.
Ms Parata said she did not feel NZQA had handled the mistake as quickly it could have.
In future, students could be able to obtain both a digital and physical version of their exam booklets. This option was already available to scholarship students.
Mr Hipkins was concerned that students would not be able to seek reconsideration of their results if they did not have a copy of their papers.
The minister confirmed two students affected by the mailing error had sought a recount.
"For any other student that might be affected, recounts are available to them by engaging with their school in the provision of other work that the students may have completed."