Apple is sending out secret ghost tweets ahead of its biggest event of the year.

The company woke up it`s entirely dormant Twitter feed this week, to much speculation about what it was up to.

But at least one of the reasons has since become clear – Apple is using Twitter to remind people about its big event, without anyone ever knowing that it has done.

When a user heads to the @Apple account, it looks dormant: a message appears informing the user that the company "hasn`t tweeted yet".

But that isn`t true, at least entirely, because people are seeing Apple tweets turn up in their Twitter feed.

The full tweet reads: "September 7 at 10 a.m. PDT. Watch the event on Apple.co/live. RT for a reminder on event day. #AppleEvent".

It also includes the same blurry picture that came on the invite to the event – and is probably a big clue to what`s going to be announced.

The phantom messages appear to be the result of Apple buying up sponsored tweets without the tweet ever actually existing before it is paid-for.

It`s not a common strategy at all, since most companies simply pay to increase the reach of a tweet they have already sent, and it`s not entirely clear how it works.

But it means that some people will see a tweet from the company, if Twitter`s data shows that they will be interested in it.

The tweet even appears to have special powers: retweeting it gives the user a reminder of the event on the day it happens.

The custom tweet includes another unusual – and expensive – product from Twitter: the custom hashtag emoji. Anyone tweeting the words #AppleEvent will find the Apple logo added next to their message.