Shocking evidence of Brandon-Lee and Toni-Lee Thulsie’s alleged involvement in potential terror attacks has been revealed in court documents.

The documents including photographs were presented by the state on Friday morning at the Johannesburg Magistrate’s Court after prosecutors were asked to prove that they had enough evidence to justify the arrest of the so-called ‘terror twins’.

The brothers were arrested earlier in July on terrorism related charges.

Authorities said the twins who also tried to travel to Syria in 2015 had been under surveillance for a few months.

On Thursday, Hawks officer Wynand Olivier says he had received foreign intelligence that Toni-Lee Thulsie was discussing the manufacture and detonation of bombs with people linked to Islamic State.

Olivier claimed that after he questioned Toni-Lee following raids on his and his twin's homes, Toni-Lee indicated that he believed in what he had done, and was prepared to go to jail.

Prosecutor Chris MacAdam has indicated that the state will apply for some of this documentation not to be made public.

The twins have applied for the search and seizure raids conducted on their homes, to be declared unlawful.