A 15-year-old has been forced to cancel her birthday party after it went viral on Facebook.

The Year Ten girl from Sydney set up the open Facebook invitation to her 16th birthday party and asked her friends to each invite a friend.

She told her friends it was "open house party as long as it dont get out of hand". (sic)

Almost 190,000 people have now RSVPed yes to the party on the Facebook page.

Although the party has now been cancelled, Chatswood Police are on standby for the event in case some of those who have RSVPed actually turn up.