African National Congress Youth League leader Julius Malema says he believes "imperialists" and "colonialists" are behind his prosecution for hate speech and harassment.

The Sonke Gender Justice Network has taken Malema to court for comments he made about President Jacob Zuma's rape accuser.

He is reported to have said the woman must have liked having sex with Zuma because she only left his house the next morning and asked him for money to get home.

Malema began giving testimony in the Equality Court on Monday.

Scores of ANCYL supporters protested outside the court and at one point threatened to derail proceedings inside.

The matter deteriorated into chaos as Malema's backers unleashed a torrent of abuse at the complainant, Mbuyisela Botha, and his legal team during a recess. The youth leader merely chuckled as the scene unfolded.

The supporters were all thrown out of court before Malema began giving evidence. In court he calmly detailed his gender activism but once outside Malema took aim at his accuser.

"When imperialists and colonizers want to collapse your government they use non-governmental organisations," said Malema.

He vowed that he would have to be forced to apologise for the comments he made.