While some have hailed the swearing in of Nigeria's new president Goodluck Jonathan as a hopeful sign of development for Africa's most populous nation, other observers see the new leader's roots as potentially unsettling for the nation's delicate balance of power, which is shared across religious lines.

Jonathan, who is from the country's Christian southern region, was sworn in on Thursday after former President Umaru Yar'Adua, a Muslim, died after a long bout with a kidney illness. Jonathan had been serving as acting president for several months.

While the power transition seemed smooth, the possibility of Jonathan extending his presidency beyond next year's elections could upset an unwritten power-sharing rule within the country's ruling People's Democratic Party, which rotates candidates between Muslim northerners and Christian southerners.

Since Yar'Adua was still in his first four-year term, some see Jonathan's presidency as a source of political unrest in the country, which is already plagued with violence between its two major regions.

Outbreaks sectarian of violence earlier this year, one in March and one in January, left more than 1,000 Nigerians dead. According to advocacy group Human Rights Watch, over 13,500 Nigerians have been killed in religious or ethnic clashes since the country's military rule ended in 1999.

In its 11th annual report released last week, the U.S. Commission on International Religious Freedom (USCIRF) recommended for the second year in a row that Nigeria be placed on the list of "countries of particular concern," which is the most severe category in a three-tier rating system.

"Having visited Nigeria three times over the past year, USCIRF has observed how unchecked waves of sectarian violence-for which no perpetrator has yet been brought to justice-have engulfed this key nation in a conflagration of impunity," the group's report reads.

"Not a single criminal, Muslim or Christian, has been convicted and sentenced in Nigeria's ten years of religious violence. Therein lies the problem," the report continues. "The Nigerian government and judicial system have so far been unwilling or unable to protect either side."

"Until this changes, we can only expect more violence. Already we are seeing the creation of conditions
for the proliferation of extremist ideology and terrorism."

Meanwhile, President Jonathan declared a day of morning for Yar'Adua as one of his first acts in power.

In his brief acceptance speech, Jonathan referred to his predecessor as "not just a boss but a good friend and brother."

"He will always occupy a place of pride in the political history of our dear nation," he said.

U.N. General Secretary Ban Ki-moon also commended the late Yar'Adua, saying that he will be remembered "for his efforts to bring peace and stability to the Niger Delta region and for his commitment to democratic governance and electoral reforms."