Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. UN: Sudan Making Arbitrary Arrests Before Referendum VOA News 06 January 2011 A 4 Jan 2011 file photo of pro-separation activists rallying outside Juba airport in southern Sudan where Sudanese President Omar al-Bashir arrived Photo: PA Pro-separation activists rally outside Juba airport in southern Sudan where Sudanese President Omar al-Bashir arrived (file photo) The U.N. human rights chief says Sudanese authorities are restricting press freedoms and making arbitrary arrests, as a referendum approaches on the independence of south Sudan. Navi Pillay said it is important the referendum is free and fair, calling it a critical moment in Sudan's history. She urged the governments of Sudan and south Sudan to quickly halt efforts to intimidate voters or taint the result of the referendum, which begins on Sunday. Nearly 4 million southern Sudanese are registered to vote in the referendum, which will allow voters to secede or remain united with the north. The vote is expected to split Africa's largest country in two.  The referendum is the centerpiece of the 2005 peace deal that ended Sudan's north-south civil war. Some information for this report was provided by AFP and Reuters. .