Outgoing Kenyan Prime Minister Raila Odinga on Saturday lodged a formal legal challenge over the outcome of presidential elections that saw him defeated by his rival Uhuru Kenyatta.

The move will be seen as a test of democracy in Kenya, which was rocked by bloody violence after the last disputed polls in 2007, when more than 1,100 were killed and hundreds of thousands were displaced.

His half brother may be the most powerful man in the world but that stardust seemed not to rub off on Malik Obama as he failed miserably to win a county gubernatorial seat in Kenya's recently concluded polls.

Obama, 54, who shares a father with United States President Barack Obama, won just 2,792 votes -- some 140,000 behind the final winner -- in his bid to claim the seat for his home area in western Kenya.

Kenyans called Sunday for reconciliation after a disputed presidential election, but calm prevailed in the country the day after results were declared, in striking contrast to the aftermath of the 2007 polls.

Uhuru Kenyatta, who faces an international trial for crimes against humanity, was Saturday declared winner. But his main rival, Prime Minister Raila Odinga, has vowed to challenge the result in court.

Uhuru Kenyatta narrowly won Kenya's presidential election Saturday, urging calm and pledging to work with rivals and cooperate with the international community.

Kenyatta, son of Kenya's founding president and one of Africa's richest men who also faces an international crimes against humanity trial, scraped by with 50.07 percent of the vote to avoid a runoff against his closest rival Raila Odinga.

Long lines of Kenyans queued from far before dawn to vote Monday in the first election since the violence-racked polls five years ago, with a deadly police ambush hours before polling started marring the key ballot.

The tense elections are seen as a crucial test for Kenya, with leaders vowing to avoid a repeat of the bloody 2007-8 post-poll violence in which over 1,100 people were killed, with observers repeatedly warning of the risk of renewed conflict.

The United States said Friday that Kenya was facing a "historic opportunity" in next week's elections as it urged all Kenyans to vote peacefully for a new president.

Leading candidates have pledged there will be no repeat of the bloodshed that followed the disputed 2007 polls in Kenya in which more than 1,100 people were killed and around 600,000 fled their homes.

Somalia's al-Qaida-linked Shebab on Wednesday issued a stark warning to Kenyan voters ahead of next week's general elections, threatening them with a "long, gruesome war".

The Islamist group argued Kenya was safer when it ruled bordering southern Somalia but stopped short of saying who Kenyan voters should choose in the March 4 polls.

At least 35 people in eastern Kenya died Wednesday when the bus they were traveling in veered out of control and rolled several times, police said.

Traffic police chief boss Samuel Kimaru said 11 people died at the scene and another 24 where being treated or on their way to hospital.

One person was killed in a bomb blast at a school in the northeastern Kenyan town of Garissa late Saturday, officials said, adding they believed the man may have been the bomber himself.

"Badly damaged body parts of a man were discovered at Garissa primary school after a loud explosion," said a senior police officer in the restive region which borders war-torn Somalia.

Somalia's Shebab insurgents claim to have executed a captured Kenyan soldier and repeated threats to kill five other hostages, the extremists said Friday.

"While the mujahedeen have executed the serving KDF (Kenya Defence Force) soldier, there is still a chance of securing the release of the remaining five prisoners," the Shebab said in a statement.