Jack Dorsey testifies during a Senate Intelligence Committee hearing on Capitol Hill in Washington, DC. File/ AFP

Twitter said Friday the account of chief executive Jack Dorsey had been "compromised" after a series of erratic and offensive messages were posted.

The tweets containing racial slurs and suggestions about a bomb showed up around 2000 GMT on the @jack account of the founder of the short messaging service.

"We're aware that @jack was compromised and investigating what happened," a Twitter spokesperson said.

Some of the tweets contained the hashtag #ChucklingSquad which was believed to indicate the identity of the hacker group.

The news comes with Dorsey and Twitter moving aggressively to clean up offensive and inappropriate content as part of a focus on "safety."