According to the Sudan News Agency, the Sudanese President Omar al-Bashir has stated that his government will tighten the application of Islamic law, or sharia, in northern Sudan if southern Sudan votes for independence next month.
"If the separation of the South unfortunately happens, the constitution will be amended and sharia will become the main source of legislation," al-Bashir said.
The enforcement of Sharia in northern Sudan was relaxed after the 2005 peace treaty ended more than 20 years of civil war - a war that pitted the northern government of Arab Muslims against blacks in southern Sudan who practice Christianity and animist religions.
Al-Bashir said recently that the separation of the South would be akin to "cutting-off a part of the nation's body but not the end of the world."
The vote is scheduled to happen January 9.
On Friday, al-Bashir sought to allay Northern fears about losing access to the Southern oil as he said that greater quantities of oil could in fact be found in the North, and also that the North would be willing to give up its share of oil revenues if the South voted for unity in the referendum.