An eight-year-old Sydney boy was accidentally exposed to a hardcore porno image while viewing the Lions ticket promotion of flag carrier Qantas on its Facebook page on Friday.

He was viewing the post on his father's iPad when he found the image which was on the Qantas Facebook page for about seven hours but as been removed since the family contacted the air carrier to complain.

Qantas explained it was spam posted in the middle of the night on its Facebook page. The inappropriate image was about the size of a profile picture, Canberra Times reported. The air carrier said it removed the image upon being informed and apologised to the family.

The father recalled that when the mouse's pointer is rolled over the image, a large version of the image with clearly recognisable anatomical details popped up. What disappointed him, besides the presence of the lewd image in an airline Facebook page, was the initial response of the Qantas that there was nothing they can do about it, while another official said there was less chance that people were exposed to the image because it was posted about midnight.

However, the father pointed that Qantas is an international carrier and Facebook is accessible 24 hours a day.

Qantas said it monitors is Facebook presence very closely with the use of various filters to prevent inappropriate content, which is a challenge that all companies that use social media face.

Last week, a male New Zealand teacher almost lost his job when he accidentally showed porn clips to his students due to a technical glitch when the computer he was using skipped the Powerpoint. However, because of his unblemished record except for the incident, the teacher was instead transferred school.