Convicted racist Vicki Momberg is facing fresh allegations of racism after she apparently told prison warders that they were under-educated and stupid, and that black people lacked intelligence.

The incident, which almost resulted in one of the warders moering her, is said to have occurred on Wednesday, when the officials were transporting her from the Randburg Magistrate's Court to Sun City prison after she was denied leave to appeal her sentence.

The explosive claims came to the fore when the warders phoned prosecutors from the court to solicit legal advice on the alleged racial labels Momberg hurled at them.

According to a court official who overheard the prison officials asking for advice on how to handle the matter, Momberg insulted them unprovoked when they were transporting her back to prison.

"They said she told them prison warders were less educated and stupid and said black people lack intelligence.

"They actually wanted to find out if prosecutors would support them if they opened a case against her. The prosecutors encouraged them to do so but the warders decided not to heed their advice," said the official.

The court official also alleged that Momberg denigrated magistrate Pravina Rugoonandan in the same exchange, saying she was also not intelligent.

Department of Correctional Services spokesman Singabakho Nxumalo confirmed that Momberg used foul language against their officials but said the insults were so crude that they could not be repeated in public.

"The matter was reported to management by the officials concerned and the inmate has been charged internally and the matter will be dealt with following DCS policies. The officials escorting the inmate indicated no desire to press criminal charges. The department will work with the inmate in correcting the offending behaviour and render relevant rehabilitation programmes.

"As a sentenced inmate, offender Momberg was transported to court by DCS officials using a state vehicle. Without divulging the full security detail, we can indicate that it was a team of male and female officials. The same officials took the inmate back to the centre [Johannesburg female correctional] where she will continue to serve her sentence as prescribed by the court," said Nxumalo.

Momberg's lawyer Kingdom Onah said he could not deny nor confirm the allegations.

"I need to get that from her," he said.

"I have not consulted with her on that matter."

Momberg, a former estate agent, is serving a two-year sentence after she was found guilty on four counts of crimen injuria in November last year after a video of her insulting police officers and using the K-word went viral on social media.

She was the victim of a smash-and-grab incident in Joburg and then insulted a black police officer who was trying to help her.