The secretive Central Intelligence Agency in the United States has joined the world of social media.

"We can neither confirm nor deny that this is our first tweet," the CIA joked on its new official Twitter page.

Within two hours of the post, it received around 90,000 retweets and the CIA counted 115,000 followers.

The Twitter Government and Politics team welcomed the posting with a #BestPractice hashtag for being "creative with your first tweet".

CIA director John Brennan said in a statement that the new Twitter and Facebook accounts aimed to help the agency "more directly engage with the public and provide information on CIA's mission, history and other developments".

"We have important insights to share," Mr Brennan said.

The agency already had accounts with YouTube and Flickr.

There's little chance the agency will post spy secrets.

Instead, it plans to post its rare press releases, information about careers within the agency or about historic missions that have since been declassified.

The agency will also post images of objects on display at the CIA museum, which it called "the best museum most people never get to see" - because it is closed to the public.

On its Twitter profile, the CIA describes itself as "the nation's first line of defence. We accomplish what others cannot accomplish and go where others cannot go."