Early on Saturday morning NSW students were able to check their mark for individual subjects using a link shared via social media.

It's understood they were not able to see their overall ATAR ranking.

The state's exam authority apologised for the mistake and confirmed final results would be released on Thursday.

"For a short period this morning, some students were able to access a preliminary set of 2022 HSC Results," a NSW Education Standards Authority spokesperson said.

"(The authority) is investigating the cause of the issue and sincerely apologises for any inconvenience caused."

The loophole was closed within hours.

NSW Education Minister Sarah Mitchell said an IT issue was to blame and apologised on behalf of the authority for causing any stress or confusion.

"I'm very disappointed this has happened and have asked (the authority) for an explanation as to how this occurred," Ms Mitchell said in a statement.

Opposition education spokeswoman Prue Car pointed the finger at the Perrottet government, claiming it had "dropped the ball on what should be a well-established process."

"This bungle has just added unnecessary stress on students, many of whom have no certainty if they were shown their final results or not," Ms Car said.

"The NSW government should give certainty to HSC students today and ensure all students can see their results equally."

Ms Mitchell hit back at the criticism which she described as a "lack of empathy for HSC students".

"It is incredibly disappointing that NSW Labor, with no understanding of the issue, chose to add to student stress and confusion," Ms Mitchell said.

A similar incident occurred in January when a list of distinguished achievers for the class of 2021 was also made available days before results were meant to be released.

Australian Associated Press