A Facebook account posing as Qantas has been outed as a scam after more than 100,000 users signed up for “free first class tickets”.

The image, posted on Facebook on Sunday, has been shared more than 102,000 times.

It has also attracted more than 85,000 likes and 15,000 comments.

Qantas alerted customers to the scam shortly after midday on Monday, via the airline’s social media accounts.

The warning stated that the airline was aware of the scam, citing a fake Facebook account.

“Facebook has been advised and are currently investigating,” it read.

“Our campaigns are always run from our authenticated Facebook page (identified by its authorised blue tick), or through the official Qantas website.”