KHARTOUM (AFP) - Sudanese President Omar al-Bashir said on Sunday that the countrys north will reinforce its Islamic law after a referendum expected to grant independence to the south. If South Sudan secedes, well change the constitution. There will be no question of cultural or ethnic diversity. Sharia will be the only source of the constitution, and Arabic the only official language, Bashir said in a speech aired on national television. Southerners are set to vote in a referendum on January 9 on whether to remain united with the north or break away and form their own country. The vote is a key plank of the 2005 Comprehensive Peace Agreement between the mainly Muslim north and predominantly Christian south that put an end to more than two decades of civil war. Analysts are predicting that the southerners will opt for independence, and senior officials in Khartoum are even beginning to get used to the idea of the split. In a speech punctuated by religious references, Bashir also defended the way the authorities have dealt with the case of a young woman whose whipping by police appeared in a YouTube video. A police spokesman said on Tuesday that 46 women and six men had been arrested for holding an illegal demonstration after the video was made public. There are people who say they feel ashamed about this sentence. They should review their interpretation of Islam because sharia has always stipulated that one must whip, cut, or kill, said Bashir.