Ryanair has issued a warning to customers over a new Facebook scam.

Over 10,000 people fell victim to a fake competition that did the rounds on Facebook today.

The post first appeared at 10.30am and claimed that the company was giving away first class flights and US$5,000 spending money to "celebrate the brand's fourth wedding anniversary".

The post soon went viral with eager social media users hoping they were in with a chance of winning the trip of a lifetime.

“We are giving you the chance to win Complimentary First Class Flights to any destination of your choice world wide and $5,000 in spending money for you and up to five friends," the post read.

“Only rules are to: 1.Like &Share this photo 2.Comment Thank You below.

“On June 18th various Lucky Winners will be selected randomly and announced on our page. Good Luck!”

Ryanair warned that it's not an official promotion and urged customers to be cautious of any competitions that comes from pages without the blue verified badge.

Online Editors