Twitter CEO Jack Dorsey's account was hacked, sending tweets and resending other tweets anyone could see including racist insults and insults on his nearly 4 million followers.

Twitter said in a tweet on Friday that it was aware of the account being compromised and investigating what had happened.

One of the tweets posted on Dorsey's account after his piracy was that Nazi leader Adolf Hitler was innocent, while others contained racist comments against African Americans and Jews.

Also on his official page, a tweet indicating the presence of a bomb in the headquarters of "Twitter".

Shortly after account hacking, abusive tweets were deleted.

The share price of "Twitter" fell by less than one percent in transactions after official trading hours after the discovery of account piracy. (Agencies)