US President Donald Trump has responded to criticism from his former secretary of state Rex Tillerson by calling him “dumb as a rock” and “lazy as hell”.

During a rare public appearance in Houston on Thursday, Mr Tillerson weighed in on his time in the administration.

He called Mr Trump “undisciplined” and said the president “doesn’t like to read, doesn’t read briefing reports, doesn’t like to get into the details of a lot of things”.

He also said Mr Trump frequently asked him to do things that he had to explain were illegal or otherwise ill-advised.

Mr Trump said in response that Mr Tillerson “didn’t have the mental capacity needed for the job” and that he “couldn’t get rid of him fast enough”.

He also praised Mr Tillerson’s replacement, Mike Pompeo.