A senior South Sudanese leader has threatened the region may unilaterally declare independence if key disagreements over a scheduled referendum are not resolved. The January 2011 vote gives South Sudan the option of choosing independence.

The secretary-general of the Sudan People's Liberation Movement, Pagan Amum, told VOA the South might simply secede if it is not satisfied with the North's handling of the independence referendum preparations.

"The [National Congress Party] is attempting to impose some obstructions and difficulties before the referendum and that is a dangerous development from the National Congress," Amum said.  "It may lead to southern Sudan declaring a unilateral independence."

Amum claims that if the referendum law is not passed by Parliament by the end of this year, the South will start considering "other options."

A key sticking point is the North's position that formal separation should require a 75 percent approval in the referendum.

The North also wants to make Southerners who no longer live in the South eligible to vote, whereas the South's SPLM party asserts that only those living in the South may participate.

Officials of the North's ruling NCP party say a unilateral declaration of independence would be a violation of the Sudanese constitution.

But Amum strongly denied such action would be unconstitutional.

"The constitution says that the people of southern Sudan shall exercise the right of self-determination, including choosing between unity or separation," Amum said.

South Sudan has accused the North of purposely stalling passage of the referendum law, raising concerns that the 2011 poll might not take place as scheduled.

The independence referendum was a core part of the 2005 peace agreement that ended more than two decades of civil war.

The fragile peace seemed to pass a crucial test this past month as a highly-anticipated ruling from The Hague over a territorial dispute has not caused any renewal of fighting.

The North has made clear its desire for Sudan to remain unified as one country.  South Sudan is currently allowed semi-autonomous governance under the peace agreement.