SAN FRANCISCO, United States (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 before being deleted.

Some of the tweets contained the hashtag #ChucklingSquad, which was believed to indicate the identity of the hacker group. The same calling card was left behind during recent hacks of other high-profile social media personalities.

The messages contained racial epithets and included a retweet of a message supporting Nazi Germany.

Twitter said that the phone number associated with Dorsey’s account was “compromised due to a security oversight by the mobile provider,” allowing a hacker to posts tweets to @jack by sending text messages.

Dorsey’s account has been secured and there was “no indication that Twitter’s systems have been compromised,” according to the San Francisco-based Internet firm.

It appeared that tweets posted on Dorsey’s account by the hacker were up for about a half-hour before they were removed.