The United Nations has criticised Sudan for jailing journalists who wrote about the alleged rape of a female opposition activist by security forces, saying rapists, not reporters, must face charges. "Regardless of the facts of the case, Sudanese journalists have a right to report on rape and other forms of sexual violence," Margot Wallstrom, the UN Special Representative on Sexual Violence in Conflict, said in a statement late on Wednesday. "Rapists -- not reporters -- must face criminal charges in the Sudan. Only by addressing sexual violence openly can we have any chance of breaking what has been called history’s greatest silence and, ultimately, rooting it out," she added. Last week, a Khartoum court jailed Amal Habani for reporting the alleged rape of Safiya Ishaq, an activist who claimed in videos posted online that she was raped repeatedly by three security officers after her arrest in the capital in February. Another female journalist had already been imprisoned in July for writing about the same case, and refusing the option of paying a fine, after she was also found guilty of publishing lies and violating Sudan's ethics code. Both have since been released, after their fine of 2,000 Sudanese pounds ($600) was paid, but at least four other journalists are awaiting trial. Media rights watchdog Reporters Without Borders has accused the Sudanese authorities of prosecuting journalists in a bid to stop them making embarrassing revelations about human rights violations by the security forces.