Johannesburg - The cross-examination of a State witness, dubbed Mr B, in a trial stemming from an alleged rightwing plot to attack the ANC's 2012 Mangaung conference continued on Monday.

Bloemfontein High Court Judge Mojalefa Rampai was hearing evidence in Johan Prinsloo's trial on charges of treason, conspiracy to take part in terrorist acts, and possession of illegal ammunition.

Johann Nel, for Prinsloo, questioned Mr B on what happened when police approached him for information in their investigation of Prinsloo.

Prinsloo, Martin Keevy, and Mark Trollip were arrested a day before the conference started at the University of the Free State, Bloemfontein, in December 2012.

Trollip pleaded guilty to a charge of conspiracy and was sentenced to eight years imprisonment last year. Keevy was declared unfit to stand trial.

The matter continues.