Twitter has said it is investigating after CEO Jack Dorsey has had his account hacked with a series of racist tweets posted online.
The flurry of offensive messages were posted to Mr Dorsey’s 4.2 million followers this evening.
A spokesperson for Twitter said: "We're aware that Jack was compromised and are investigating what happened."
The offensive tweets - which included false reports of a bomb threat at Twitter HQ - were quickly deleted.
The account also re-tweeted posts from several individuals claiming to be responsible.